diff --git "a/.lancedb/cbse.lance/data/770c23a4-0ec1-49d6-92e7-c0a09e8a8d20.lance" "b/.lancedb/cbse.lance/data/770c23a4-0ec1-49d6-92e7-c0a09e8a8d20.lance" new file mode 100644--- /dev/null +++ "b/.lancedb/cbse.lance/data/770c23a4-0ec1-49d6-92e7-c0a09e8a8d20.lance" @@ -0,0 +1,8361 @@ +How Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt + 1 + +Revision Notes +Class 10 – Science +Chapter 8 – How do Organisms Reproduce? + +1. Do organisms create exact copies of themselves? + +● The organisms are similar in their looks due to having similar body +designs, which in turn indicates that the source for these designs must +be similar. And hence reproduction is that process where these designs +are created. +● The nucleus of a cell contains t he chromosomes , which carry the +information for the inheritance of features from parents to the next +generation. It is present in the form of DNA molecules . +● The DNA present in the nucleus of a cell is the source of information +for making proteins. If this information changes, then a different set of +proteins will be synthesised which will eventually lead to altered body +designs in the organisms. +● Hence it can be noted that a basic event in reproduction involves the +creation of a DNA copy. +● This copying of D NA is accompanied by the creation of an additional +cellular apparatus, after which the DNA copies separate with each of +them having its own cellular apparatus. Thus, a cell divides to give rise +to two cells. +● Since this process of copying DNA is a biochemi cal process, it may not +be reliable and it will lead to some variations each time. +● If the created new DNA copy is not viable, then the cell will not +survive. And the surviving cells will be similar but may not be identical +to the original and will subtly differ from each other. + +1.1. The importance of variation +● The consistent DNA copying that happens during reproduction is +essential to maintain the features of body design of an organism so that +it can occupy its well -defined space or niche in the ecosystem. +● Hence reproduction is very much linked with the stability of a +population of a spec ies. +● The variations become important here as an organism may be suited forHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +● The consistent DNA copying that happens during reproduction is +essential to maintain the features of body design of an organism so that +it can occupy its well -defined space or niche in the ecosystem. +● Hence reproduction is very much linked with the stability of a +population of a spec ies. +● The variations become important here as an organism may be suited for +a specific niche and a drastic change in that due to unforeseen +environmental conditions makes their survival difficult. + 2 + +● Hence in such situations when a few among the species have some +variations, they stand a chance of survival in the new niche. And thus, +these species adapt themselves to the new conditions and the species +are maintained over a period of time. +● It can be understood with an example. If a species of bacteria is livin g +in the temperate waters and suddenly the temperatures rise due to +global warming, then most of the bacteria in that water would not +survive. But maybe a few variants among them who are able to resist +the heat may survive and grow. In case the variations were not present, +that entire species of bacteria would have become extinct. +● Thus, the importance of variation lies in the survival of a species +over time. + +2. Modes of reproduction + +Reproduction can be defined as a process that involves the production of an +offspring by a particular individual or individuals with the aim of propagating +their species. Generally, reproduction happens during the reproductive phase +of an organism. The mode of reproduction may vary in organisms. They can +be broadly categorised as: +a) Asexu al mode of reproduction: +● The mode of reproduction by means of which a single individual +creates a new generation of species is termed as asexual +reproduction. +● Generally unicellular organisms exhibit asexual mode of +reproduction, though some of them exhibit sexual mode too. +b) Sexual mode of reproduction:How Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +be broadly categorised as: +a) Asexu al mode of reproduction: +● The mode of reproduction by means of which a single individual +creates a new generation of species is termed as asexual +reproduction. +● Generally unicellular organisms exhibit asexual mode of +reproduction, though some of them exhibit sexual mode too. +b) Sexual mode of reproduction: +● The mode of reproduction by means of which two individuals take +art in the creation of a new generation of species is termed as sexual +reproduction. + +Types of asexual mode of reproduction : +2.1. Fission: +● In unicellular organisms the new individuals are created by the process +of cell division or fission. +● The nucleus of the cell divides into new individual cells under +favourable conditions. +● Fission can be of two types depending on the number of new +individuals created. + + 3 + +a) Binary fission : This division leads to the formation of two new +individuals. These can be further divided based on their plane of +division as: +i. Irregular binary fission : In this type of fission the plane of +division of a cell is irregular, it can be in any plane. Example - +Amoeba. +ii. Transverse binary fission : In this type of fission the cells divide +along a transverse plane. Example - Paramecium. +iii. Longitudinal binary fission : In this type of fission the plane of +cell division is lon gitudinal. Example - Euglena . + +b) Multiple fission : This is the division of a single cell into many new +daughter cells. Example - Plasmodium . + +2.2. Fragmentation: +● This is a process where an organism simply breaks up into smaller +pieces when they are mature. +● Each of the fragments or broken pieces grow into a new individual. +There should be a cell that is capable of growing into a new individual +in such organisms. +● Example - Spirogyra. + +2.3. Regeneration: +● This is a process where some fully differentiated organism s can be cutHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +● This is a process where an organism simply breaks up into smaller +pieces when they are mature. +● Each of the fragments or broken pieces grow into a new individual. +There should be a cell that is capable of growing into a new individual +in such organisms. +● Example - Spirogyra. + +2.3. Regeneration: +● This is a process where some fully differentiated organism s can be cut +or broken into pieces and each of their body parts have the ability to +grow into a new individual . +● Different cells in this mass of cut cells undergo a lot of changes in an +organised manner to become different cells and tissues. +● Example - Planaria , Hydra . + +2.4. Budding: +● This is a process where a protuberance like outgrowth which is called +as bud grows by repeated cell division at a specific site and then they +detach from the parent body to develop into a separate individual +organism. +● Example - Hydra. + +2.5. Vegetative propagation +This is the mode of reproduction by which plants reproduce asexually. +In this mode, new plants are developed from a plant’s vegetative parts + 4 + +like stem, leaf, root . There are different methods of vegetative +propagation that are carried out in plants which are as follows: +a) Stem cutting : This involves cutting the stem into small pieces +having internodes and axillary buds. These are then planted in the +soil to propagate into new plants. This method is used in sugarcane, +hibiscus, drumstick etc. +b) Layering: This is a method where the young stem of a plant is bent +and buried in the soil to develop roots and thus a new plant. Once +the new plant develops, the stem is detached from the parent plant. +This is used in jasmine, bougainv illaea. +c) Grafting : This is a method wherein the stems of two different +plants are cut and joined together to unite and start developing into +a new plant. This is used in nutmeg, roses etc.How Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +and buried in the soil to develop roots and thus a new plant. Once +the new plant develops, the stem is detached from the parent plant. +This is used in jasmine, bougainv illaea. +c) Grafting : This is a method wherein the stems of two different +plants are cut and joined together to unite and start developing into +a new plant. This is used in nutmeg, roses etc. +d) Leaf buds : This is a method in which the buds in the notches of +leaves develop into new plants. This can be seen in bryophyllum. + +Advantages of the vegetative propagation : +a) The plants that are grown by vegetative propagation bear flowers and +fruits earlier as compared to the plants produced from seeds. +b) All plants that are produced this way are genetically similar to the +parent plant a nd have all its character istics . + +2.6. Spore formation: +● Many multicellular organisms have specific reproductive parts. +● They have tiny thread -like structures with a blob called sporangia . +● These contain cells or spores which eventually develop into new +individuals. The spores are very light and covered by a thick wall to +protect them and when they come in contact with a moist surface they +start to grow. +● Example - Rhizopus. + +3. Sexual Repro duction: + +3.1. Why the sexual mode of Reproduction? +● The sexual mode of reproduction involves two organisms, a male and a +female to create a new organism or offspring. +● The sexual reproduction allows greater variations in a species as the +two individuals involved in producing the offspring would have +different patterns of variations. This process includes the combination + + 5 + +of DNA of two different individuals and the resultant combination and +variation would be unique. +● Hence this ensures a mixing of the gene pool of the species within a +population and it also ensures the survival of the species as this process +generates more variations due to the genetic recombination.How Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt + 5 + +of DNA of two different individuals and the resultant combination and +variation would be unique. +● Hence this ensures a mixing of the gene pool of the species within a +population and it also ensures the survival of the species as this process +generates more variations due to the genetic recombination. +● The process of combining DNA of two different indiv iduals during +sexual reproduction will lead to an offspring with twice the amount of +DNA than their previous generation. +● The solution to this lies in the fact that there are certain specialised cells +in such organisms called germ cells or gametes . These ha ve half the +number of chromosomes and, therefore half the amount of DNA in +comparison to the other non -reproductive cells. The combination of +these germ cells from two different individuals during the process of +sexual reproduction restores the original nu mber of chromosomes and +DNA content in the new offspring. +● The germ cells may be similar and not much different from each other +in simple organisms. With the complexity of the organisms the germ +cell also becomes specialised. One of the germ cells becomes large and +stores food. This is known as the female gamete . The other germ cell +which is small and motile is called the male gamete . These gametes +lead to the differences in the bodies and reproductive systems of males +and females. + +3.2. Sexual Reproduction in flowering plants +● The process of sexual reproduction in plants involves the fusion of +gametes to produce offspring . The reproductive parts in angiosperms +[plants that flower and produce fruits and seeds] are located in the +flower. The parts of a flower consist of sepals, petals, stamens and +pistils . +● The reproductive parts of the flower are stamen which contains the +male gamete and the pistil containing the female gametes. +a) Stamen : This is the male reproductive part and is also known as theHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +[plants that flower and produce fruits and seeds] are located in the +flower. The parts of a flower consist of sepals, petals, stamens and +pistils . +● The reproductive parts of the flower are stamen which contains the +male gamete and the pistil containing the female gametes. +a) Stamen : This is the male reproductive part and is also known as the +androecium. It consists of a filament and an anther that encloses the +pollen grains. The pollen grains produce the male germ -cells or +gametes. +b) Pistil : This is the female reproductive part of the flower and is also +known as gynoecium. This is made of three parts, namely, stigma, +style and ovary. The enlarged portion at the bottom of a pistil is the +ovary that contains an ovule with an egg cell . The middle long part +of the pistil is the style and the term inal sticky part is the stigma . + 6 + +● Based on the presence of the stamen or pistil, flowers can be classified +as: +a) Unisexual : These are the flowers that contain either stamens or +pistils. These are also called incomplete flowers. Example - papaya, +mulberry, watermelon etc. +b) Bisexual : These are flowers that contains stamens as well as pistils. +Example - Hibiscus, mustard, rose etc. +● The process of sexual reproduction in plants starts with the fusion of +the male and the female gametes, followed by the formation of a zygote +that eventually develops into a new plant. The process is explained as +follows: +a) Pollination: +● The process of sexua l reproduction in plants starts with the transfer +of pollen grains from the anther of the stamen to the stigma of the +pistil. This process is termed as pollination. +● This is facilitated by pollinating agents like wind, birds, animals, +water etc. which tran sfer the pollen grains. +● There can be two types of pollination as follows: +i. Self-pollination : This involves the transfer of pollen grains fromHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +of pollen grains from the anther of the stamen to the stigma of the +pistil. This process is termed as pollination. +● This is facilitated by pollinating agents like wind, birds, animals, +water etc. which tran sfer the pollen grains. +● There can be two types of pollination as follows: +i. Self-pollination : This involves the transfer of pollen grains from +the anther to the stigma of the same flower. Example - wheat, +peanut, etc. +ii. Cross -pollination : This type of pollination involves the transfer +of the pollen grains from the anther of one flower to the stigma of +another flower of the same species. Example - apples, pumpkin +etc. +b) Fertilization: +● Through the process of pollination, the pollen is deposi ted in the +style of the pistil. For the next process in reproduction, it needs to +reach the female germ -cells which are present in the ovary. +● To facilitate this, a tube grows out of the pollen grain and reaches the +ovule in the ovary of the pistil. +● Here in the ovule the male germ -cell fuses with a female germ -cell to +form a zygote . This process of fusion of the gametes is termed as +fertilisation. +● After the process of fertilization, the zygote thus formed, divides +repeatedly to form an embryo inside the o vule. The ovule later +develops into a seed. +● And meanwhile the ovary grows and ripens into a fruit and the other +parts of the flower, namely the petals, sepals, stamens, style and +stigma may be shed off. + 7 + +● The seed present inside the fruit encloses the future plant in its +embryo . +c) Germination: +● The seed that contains the new plant or embryo develops into a +seedling when the conditions are suitable. This process is termed as +germination. Certain conditions like nutrients , water and proper +temperature are necessary for the process of germination. +● The embryo gets its food from the reserve food material stored in theHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +embryo . +c) Germination: +● The seed that contains the new plant or embryo develops into a +seedling when the conditions are suitable. This process is termed as +germination. Certain conditions like nutrients , water and proper +temperature are necessary for the process of germination. +● The embryo gets its food from the reserve food material stored in the +cotyledons . It also has a protective outer covering known as seed +coat. + +3.3. Reproduction in Human Beings. +● The mode of reproduction in human beings is sexual mode. The +reproductive phase of an individual is that phase of life when the +individual is ready to reproduce an offspring. Changes are noticed at +every phase of growth right from birth. +● But there are some changes that begin in the teenage age that start to +prepare us for the reprod uctive phase of life. This period of +adolescence leads to sexual maturation. The body needs to create +specialised germ -cells to take part in the sexual reproduction. The +period of maturation of the reproductive tissues in the body is termed as +puberty. +● Numerous changes are noticed in both boys and girls during this period. +The boys start to have hair growth on their face and body, voice +change, active functioning of sweat and sebaceous glands, enlargement +of penis etc. The changes in the girls include grow th of pubic hair, +enlargement of breasts, oily skin leading to pimples, onset of +menstruation etc. Both of them undergo changes in their body +appearance and they become more conscious of these bodily changes. +● The process of fusion of germ -cells in sexual reproduction, the actual +transfer of these germ -cells needs to be done. For the same special +organs need to be present like penis in males and uterus in females for +carrying the baby. + +3.3.1. Male reproductive system +● The male reproductive system consists of organs that produce +and transport the male germ -cell or gamete, male hormoneHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +● The process of fusion of germ -cells in sexual reproduction, the actual +transfer of these germ -cells needs to be done. For the same special +organs need to be present like penis in males and uterus in females for +carrying the baby. + +3.3.1. Male reproductive system +● The male reproductive system consists of organs that produce +and transport the male germ -cell or gamete, male hormone +testosterone and the organs which facilitate the discharge of male +germ -cells into the female reproductive system for fertilization. + + 8 + +● The male gamete is the sperm which is a tiny body containing +the genetic material and they have a long tail for motility to help +them reach the female germ -cell for fertilization. +● The system consists of some external organs like penis, scrotum, +testes and int ernal organs like urethra, prostate and seminal +vesicles. + + +a) Testes: Testes is the part that is responsible for the production of +the male germ -cell or sperms and the male hormone +testosterone . Testes are present in a structure known as scrotum , +located outside the abdominal cavity. This is thus located +because the formation of sperm requires a temperature that is +lower than the normal body temperature. The hormone +testosterone plays a role in regulating the formation of sperms +and also the deve lopment of the secondary sexual characteristics +that are seen in boys during puberty. +b) Vas deferens : The sperms that are produced in the testes are +stored in the epididymis . Vas deferens is a tube that transports +these sperm to the urethra. +c) Urethra : This is a common passage for the sperm as well as +urine. The same passage connects the urinary bladder and the vas +deferens. +d) Prostate gland and seminal vesicles : These glands are located +along the vas deferens . They secrete a fluid, called semen that +nourishes the sperm. This semen helps in the easier movement of +sperms.How Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +these sperm to the urethra. +c) Urethra : This is a common passage for the sperm as well as +urine. The same passage connects the urinary bladder and the vas +deferens. +d) Prostate gland and seminal vesicles : These glands are located +along the vas deferens . They secrete a fluid, called semen that +nourishes the sperm. This semen helps in the easier movement of +sperms. + + + 9 + +3.3.2. Female Reproductive System. +● The female reproductive system includes the organs that produce +the female germ -cells, provides site for fertilization of the +gametes and development of the embryo into a new individual. +● The female gametes are the eggs that are produced in the ovaries. +● They also produce some hormones like estrogen and +progesterone that are responsible for the onset of secondary +sexual characteristics in girls at puberty. +● This system includes a pair of ovaries, a pair of oviducts, uterus +and vagina that opens externally through the urethra . + + + +a) Ovaries : The ovaries are a pair of glands that are located on +either side of the uterus. The ovaries protect the female gametes +or eggs and make them suitable for fertilization. At birth the +ovary of a girl contains thousands of eggs that are immature. +After puberty, when the eggs mature, the ovaries release one egg +every month. The ovaries also produce the hormones oestrogen +and progesterone that are essential in bringing the secondary +sexual changes in a girl at puberty. +b) Fallopian tube : This is also known as oviduct . This is a thin +tube that connects the ovaries to the uterus. The eggs that are +released by the ovary are transported through this tube. +c) Uterus : This is a bag-like muscular elastic structure into which +the two oviducts open. The uterus is the site where the fertilized +egg is implanted and it grows into a foetus. It is made of 3 +tissues, outer perimetrium, middle layer of myometrium a nd theHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +tube that connects the ovaries to the uterus. The eggs that are +released by the ovary are transported through this tube. +c) Uterus : This is a bag-like muscular elastic structure into which +the two oviducts open. The uterus is the site where the fertilized +egg is implanted and it grows into a foetus. It is made of 3 +tissues, outer perimetrium, middle layer of myometrium a nd the +inner endometrium. This is also responsible for supporting the +developing foetus during the entire gestation period. + + 10 + +d) Cervix : This is the site where the uterus opens into vagina. This +facilitates a passage for the entry of the sperm into the uterus. + +Fertilization and development: +● The process of fertilization of a male and female gamete or +sperm and egg starts when the sperm enters the female +reproductive system through the vaginal passage during a sexual +intercourse. From the vaginal passage they move up through the +uterus towards the fallopian tubes. +● The eggs are present in the fallopian tube, meet the sperm and get +fertilized. +● The fertilized egg, which is known as the zygote, starts dividing +repeatedly and travels down the fallopian tube to the uterus. +● The ball of cells or embry o gets implanted in the endometrial +lining of the uterus and continues to grow into a foetus. The +embryo gets its nourishment from the mother through a special +tissue called the placenta which acts as a connection between the +mother and the developing embr yo. It helps to transport glucose +and oxygen to the embryo and remove the wastes generated by +the embryo. +● It takes about nine months for the complete development of the +child inside the mother’s body. The child is born due to the +rhythmic contractions of the uterine muscles. + +3.3.3. What happens when the egg is not fertilized? +● An egg is released by the ovary every month in anticipation of itHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +and oxygen to the embryo and remove the wastes generated by +the embryo. +● It takes about nine months for the complete development of the +child inside the mother’s body. The child is born due to the +rhythmic contractions of the uterine muscles. + +3.3.3. What happens when the egg is not fertilized? +● An egg is released by the ovary every month in anticipation of it +getting fertilised. In case the egg does not get fertilized, it can +survive for only a day. Similar to the ovary releasing an egg +every month, every month, the uterus too prepares itself to the +fertilized egg by creating a thick and spongy lining in order to +provide nourishment to the embryo. +● When the fertilization does not occur, this lining too is not +required and this lining and the egg is shed as blood and mucous +through the vagina. This is called menstruation . This cycle occurs +every month and lasts for about 2 - 8 days roughly. + +3.3.4. Reproductive Health. +● The process of sexual maturation is a gradual one which happens +while the general body growth is ongoing. Some amount of + + 11 + +sexual maturation does not prepare a young person to be sexually +active or get married and bear children and bring them up. +● Reproductive health deals with all these aspects concerned with +healthy and safe sexual practices. It becomes difficult for the +young people to make the correct choice given the various types +of pressure they face from peers, family, society. +● Lack of proper information and unhealthy sexual practices can +lead them to contract some diseases from one partner to another +and even to the offspring as a sexual act is an intimate physical +contact between them. The diseases transmitted in this manner +are termed as sexually transmitted diseases (STDs), like +bacterial infections such as gonorrhoea an d syphilis, viral +infections such as warts and HIV. These can lead to healthHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +lead them to contract some diseases from one partner to another +and even to the offspring as a sexual act is an intimate physical +contact between them. The diseases transmitted in this manner +are termed as sexually transmitted diseases (STDs), like +bacterial infections such as gonorrhoea an d syphilis, viral +infections such as warts and HIV. These can lead to health +complications and be fatal too if left untreated. +● Reproductive health covers the area of safe sex to help young +people. Pregnancy is a risk in a sexual act. As pregnancy is very +demanding for the body and mind and has to be planned, +unwanted pregnancies and abortions can be avoided by using +some contraceptive methods . +● The contraceptive methods can be by using physical barriers that +block the entry of sperm into oviducts and not let ting fertilization +take place. Examples are condoms or coverings on the penis. +● Contraceptive devices like Copper -T or intrauterine +contraceptive device (IUCD) that are implanted in the uterus +which does not allow the sperm to travel ahead. +● The other contraceptive method changes the hormonal balance of +the body, preventing fertilization . These are mostly in the form of +drugs which can be taken orally in a scheduled manner. +Examples are pills like Mala D, I -pill etc. +● Another method is the surg ical one like vasectomy in males in +which the vas deferens is blocked to prevent the transfer of +sperm. In females, tubectomy is done which blocks the fallopian +tube and thus prevents the egg from reaching the uterus. The +surgical methods are more reliable and safer as compared to the +other methods. +● Though surgery is used to abort unwanted pregnancies, it has +been widely misused by the people, especially for illegally +aborting a female foetus. + + + 12 + +● There is a law in place to prevent this female foeticide (killing of +a foetus), which states that prenatal sex determination isHow Do Organisms Reproduce CBSE class 10 Notes Science Chapter 8 [PDF].txt +other methods. +● Though surgery is used to abort unwanted pregnancies, it has +been widely misused by the people, especially for illegally +aborting a female foetus. + + + 12 + +● There is a law in place to prevent this female foeticide (killing of +a foetus), which states that prenatal sex determination is +prohibited. +● A proper ratio of males to females is essential to maintain a +balance in the society and to have a healthy population too.Sources of Energy CBSE class 10 Notes CBSE Science Chapter 14 [PDF].txt + 1 +Revision Notes +Class - 10 Science +Chapter 1 4 - Sources of Energy + Characteristics of a good fuel: +1. High calorific value +2. Less smoke +3. Less residue after burning +4. Easy availability +5. Inexpensive +6. Easy to store and transport + + Fossil fuels: +o Plant and animal remains were buried under the earth and subjected to +high temperature and pressure conditions millions of years ago, +resulting in the formation of lava flows. +o For example, coal, petroleum , and so forth. +o These fossil fuels are non-renewable energy sources that contribute +to pollution in the environment. + + Thermal power plants: +1. Thermal electricity is generated from coal, petroleum, and natural +gas. +2. The transmission of electricity is very efficient. +3. The steam generated by the combustion of fossil fuels powers the +turbine , which generates electricity . + + Hydro power plant: + + + 2 + + +1. It is the most common form of renewable energy , derived from water +falling from vast heights . +2. It is a non-polluting and clean source of energy. +3. Dams are built to catch water flowing via high -altitude Rivers. There +is a lot of potential energy in the stored water. +4. When water falls from a height, potential energy is converted to +kinetic energy , which rotates the turbines to produce electricity . +Disadvantages of Hydro power plant: +1. Construction is extremely costly . +2. Dams are not feasible on all riverbeds. +3. Submergence of large areas of human settlement and agricultural +lands. +4. People are confronted with social and environmental issues. + + Non-conventional sources: +1) Bio Mass: + + + 3 + +o It is the source of our country's routinely used fuels. +o Cow dung cakes, firewood, coal, and charcoal , for example. +o Bio gas is a combination of gases created when biomass decomposes inSources of Energy CBSE class 10 Notes CBSE Science Chapter 14 [PDF].txt +lands. +4. People are confronted with social and environmental issues. + + Non-conventional sources: +1) Bio Mass: + + + 3 + +o It is the source of our country's routinely used fuels. +o Cow dung cakes, firewood, coal, and charcoal , for example. +o Bio gas is a combination of gases created when biomass decomposes in +the absence of oxygen (Anaerobic Respiration). +o Biogas is primarily composed of methane . +o Animal dung, sewage, agricultural leftovers, vegetable wastes, chicken +droppings, and other wastes are utilised in Bio gas plants to make Bio +gas. + +2) Wind Energy: + + + 4 + +o Mechanical and electrical energy can be converted from it. +o Wind turbines, which are used to lift water, use kinetic energy from +the wind. +o Benefits: +1. Environment friendly +2. Renewable +o Disadvantages: +1. Wind speed is not always consistent. +2. Requires a big space to construct a series of wind turbines. +3. A significant quantity of capital is required. +4. The output is lower than the investment. + +3) Solar Energy: + + + 5 + +o Solar cells can convert solar energy into electricity (photovoltaic +cells). +o Photovoltaic cells use silicon solar cells to convert solar radi ation +into electricity. +o A solar panel is made up of solar cells arranged on big flat sheets. +o Solar cookers have a big glass plate and are painted black on the +outside to capture solar energy through the greenhouse effect. +o Advantage of Solar cookers: +1. Eco friendly +2. Renewable +3. Used in rural areas. +4. Retains all the nutrients in food due to slow cooking. +o Disadvantages of solar cooker: +1. Silicon cells are not cheap. +2. Solar radiation is not uniformly distributed across the +Earth's surface. +3. Not suitable for usage at night or on foggy days. +4. Cannot be used to make fried chapattis because they requireSources of Energy CBSE class 10 Notes CBSE Science Chapter 14 [PDF].txt +1. Eco friendly +2. Renewable +3. Used in rural areas. +4. Retains all the nutrients in food due to slow cooking. +o Disadvantages of solar cooker: +1. Silicon cells are not cheap. +2. Solar radiation is not uniformly distributed across the +Earth's surface. +3. Not suitable for usage at night or on foggy days. +4. Cannot be used to make fried chapattis because they require +a temperature of at least +140 C . (Only a solar cooker can +reach a maximum temperature of +100 C .) +o Solar water heater, Solar furna ce, etc. are the other solar +devices. +4) Geo Thermal Energy: +o Geo thermal energy is a type of energy that is derived from the +sun's heat . + + + 6 +o When this heat melts the rocks, magma is created. +o Magma is the term for molten rocks and hot gases. +o Magma collects at various depths under the earth's surface. These +are known as " Hot Spots " because when underground water +comes into touch with them, it turns into steam , which may be +used to generate power . +o Advantages of Geo thermal energy: +1. Renewable +2. Inexpensive +o Disadvanta ges of Geo thermal energy: +1. Very few sites available for harnessing energy. +2. Expensive + +5) Nuclear Energy: +o Nuclear energy is the energy released when the nucleus of an +atom of a substance undergoes changes. +o It is utilised as a source of heat and as a fuel for marine boats. +o Advantages or Nuclear Energy: +1. Alternative source of energy due to depletion of fossil fuels. +2. A significant amount of energy is released from a small +amount of fuel. +o Disadvantages of Nuclear Energy: +1. Risk of nuclear waste leakage +2. Expensive nucl ear plant construction +3. Pollution of the environment + +6) Energy from the sea: +o Tidal Energy in India: Gulf of Kutch, Gujarat, and West +Bengal – + Relies on tidal action to control the rise and fall of sea level. + Dams are built across a narrow stretch of sea , and a turbineSources of Energy CBSE class 10 Notes CBSE Science Chapter 14 [PDF].txt +o Disadvantages of Nuclear Energy: +1. Risk of nuclear waste leakage +2. Expensive nucl ear plant construction +3. Pollution of the environment + +6) Energy from the sea: +o Tidal Energy in India: Gulf of Kutch, Gujarat, and West +Bengal – + Relies on tidal action to control the rise and fall of sea level. + Dams are built across a narrow stretch of sea , and a turbine +converts tidal energy to electricity. + The main disadvantage for using this is that, there is no +consistent tidal action . +o Wave Energy: + Turbines are rotated by the kinetic energy of sea waves. + These turbines produce electricity.Management of Natural Resources CBSE class 10 Notes CBSE Science Chapter 16 (PDF).txt + + 1 + + + +Revision Notes +Class 10 Science +Chapter 16 - Management of Natural Resources + +● Natural resources are naturally occurring assets that are used to sustain life +and meet our daily needs. +● It includes forests, water, coal, natural gases, and petroleum reserves. +● Depletion i.e., reduction in number or quality of natural resources is +increasing at an alarmi ng rate. +● We should use our resources wisely so as to sustain the resources and conserve +our environment. +● One such measure to protect our environment was the Ganga Action Plan +(GAP) taken by the national body to conserve River Ganga because it +contained disease -causing microorganisms . +● We must follow three R’s to protect our environment and these are: +1. Reduce: Means to use less or to reduce our daily consumption of resources. +For example: Use less water for bathing, walking or cycling to save petrol +2. Recycle: This means processing wastes like plastic, paper, metals to new and +usable products again. +3. Reuse: The p rocess of using things again and again in order to protect the +environment . +For example: Using same cloth bag for shopping rather than using many +polythene bags +● Reusing the substances again is best because it does not need any external +energy for the thin gs to be used again. + +Why do we need to manage our resources? +● Because the resources available to us are limited and take millions of years to +form. +● With the human population increasing at a tremendous rate the demand for +resources is also increasing which increases the use of resources. +● Exploiting or reckless use of natural resources causes damage to the +environment. +● The management of natural resource s should be in a sustainable manner so +that these will last for generations to come. + + 2 + + + +● And should be available to everyone i.e., should be equally distributed to +everyone.Management of Natural Resources CBSE class 10 Notes CBSE Science Chapter 16 (PDF).txt +● Exploiting or reckless use of natural resources causes damage to the +environment. +● The management of natural resource s should be in a sustainable manner so +that these will last for generations to come. + + 2 + + + +● And should be available to everyone i.e., should be equally distributed to +everyone. + +Forest and wildlife: +● Forests are called the lungs of earth because it provides oxyge n which is our +most important demand for survival +● We depend on forests directly or indirectly for our survival. It provides home +and food to innumerable species. +● Forests also offer watershed protection, prevent soil erosion and floods and +reduce climate change. +● Stakeholders: +Stakeholders are the people who depend upon forests for various perspectives +of life. These include, +a. The forest department of the country +b. The industrialists +c. The wildlife and nature enthusiasts +● Some examples of local people working for the conservation of forests include +the case of the Bishnoi community in Rajasthan who protected ‘khejri’ trees +in Kheja rli village near Jodhpur in Rajasthan. +● We have to conserve forests. The importance of forests cannot be +underestimated. +● Forest resources should be used in a manner that is both environmentally and +developmentally beneficial. +● Sustainable development: +● Sustainable development is the idea of utilizing natural resources in present +without compromising the need of future generations. +● It can be achieved by using the resources judiciously and realizing the fact +that if these resources get exhausted it will create problems. + +Water for all: +● Water is a basic necessity for all biotic life. All organisms need water to exist +and survive. +● Water is essential because our daily activities are dependent on water. +● The lack of water and consumption of contaminated water can cause serious +health issues . +● Despite havingManagement of Natural Resources CBSE class 10 Notes CBSE Science Chapter 16 (PDF).txt +that if these resources get exhausted it will create problems. + +Water for all: +● Water is a basic necessity for all biotic life. All organisms need water to exist +and survive. +● Water is essential because our daily activities are dependent on water. +● The lack of water and consumption of contaminated water can cause serious +health issues . +● Despite having +71% water available on earth in many areas water scarcity has +been observed since the freshwater is only +3% . + 3 + + + +● Despite nature’s monsoon bounty in India, we are unable to sustain +underground water and water pollution has resulted in the loss of vegetation +cover. +● Rainwater harvesting (for rec harging groundwater ), irrigation using dams, +tanks, and canals help to sustain water resources. + +● Dams: +⮚ It is the structure used to control the flow of water in rivers and canals. +⮚ It is used to convert the kinetic energy of flowing water to electrical energy +with the help of motors. +⮚ The dam is a good alternative for non -renewable sources of energy and also +causes less harm to the environment. +⮚ It also helps in water storage which cou ld be used at the time of water shortage +in the area. +⮚ The dam also assures the consistent flow of water in rivers and prevent floods +and drought -like situations +⮚ Although, the dam has adversely affected marine life as well as humans. + +● Water harvesting: +⮚ Water harvesting is the process of collecting rainwater and reusing it rather +than making it run away. +⮚ It is an age-old concept in India used in many states of India. +⮚ Water harvesting techniques have many benefits such as help in irrigation, +helps to recha rge the natural well, etc. +⮚ Giving people control over their local water resources ensures that +mismanagement and over -exploitation of these resources will be reduced. +⮚ The advantages of groundwater are that it does not evaporate and does notManagement of Natural Resources CBSE class 10 Notes CBSE Science Chapter 16 (PDF).txt +⮚ Water harvesting techniques have many benefits such as help in irrigation, +helps to recha rge the natural well, etc. +⮚ Giving people control over their local water resources ensures that +mismanagement and over -exploitation of these resources will be reduced. +⮚ The advantages of groundwater are that it does not evaporate and does not +provide breedi ng grounds. + +● Coal and petroleum: +⮚ Coal and petroleum were formed from the degradation of fossils millions of +years ago. +⮚ These are resources that will be exhausted in the future no matter how +carefully we use them still we should use them in a sustainable manner. +⮚ Combustion of coal and petroleum gives out products like carbon dioxide, +water, oxides of nitrogen, and oxides of sul phur which are poisonous at high +concentrations . + 4 + + + +⮚ Carbon dioxide is a greenhouse gas which when increased leads to global +warming. +⮚ Therefore, we need to use these resources judiciously and look for alternative +sources of energy like solar energy, wind energy, etc. + +● An overview of natural resource management: +⮚ Natural resources are not available in abundance so we should realize that +selfish goals will lead to the misery of lots of people. +⮚ Sustainable management of natural resources is becoming important despite +being a difficult task. We should try our best to conserve them . +⮚ And use the natural resources very wisely so that our coming generation c an +also benefit.Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt + 1 +Revision Notes +Class 10 Science +Chapter 9 – Heredity and Evolution + +1. Accumulation of variation during Reproduction : + Reproduction is a process that gives rise to new offspring that are similar +to the parents but with some variations between them due to the process +of DNA copying . + It may be noted that these differences are slightly visible in asexual +reproduction as in p lants, but they are greater variations and diversity in +the case of sexual reproduction which involves the fusion of two different +gametes . + This leads to the variations that are seen in each generation. + These variations may be advantageous or disadvantag eous to the +individuals and may or may not enable them to cope with the changing +environmental conditions. For example , the bacteria that can tolerate +higher temperature s would survive the heat waves. + These variations accumulate over generations in the ev olutionary process +owing to the environmental factors and lead to the formation of new +species and are equally important for their survival. + +2. Heredity: + The biological process that maintains or passes on the characteristics and +traits of the parents to their offspring is termed heredity . Example, colour +of skin or hair, eyes, height etc. + This is responsible for maintaining the variations in generations an d thus +the evolution of species over a period of time. + +2.1 Inherited traits : + The characteristics that are inherited fr om the parents are termed as traits , +like eye colour or skin colour in humans. If the parent has brown and black +eyes, then the offspring may inherit a brown or black or a combination of +both. + This depends on the set of genes responsible for that trait. + The traits that are inherited in this manner are termed inherited traits and +these are the cause of the variations in the population, tho ugh everyone has +a similar basic feature.Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +eyes, then the offspring may inherit a brown or black or a combination of +both. + This depends on the set of genes responsible for that trait. + The traits that are inherited in this manner are termed inherited traits and +these are the cause of the variations in the population, tho ugh everyone has +a similar basic feature. + +2.2 Rules for the Inheritance of traits - Mendel’s contributions: + + 2 + The rules of inheritance comes from the fact that both the parents +contribute equally to the development of the traits in the offspring. + Gregor Johann Mendel , often referred to as the ‘ Father of genetics’ was +a pioneer who used his science and mathematics knowledge to frame the se +laws of inheritance. He did so using pea plants for his experiment s as he +found them easy to grow and they had g reater number of visible +characteristics like ta ll/short, white/violet flowers, round/wrinkled seeds. + Mendel found during his experiments that there were some factors +controlling the traits, which are now known as genes . + The genes are present as a pair f or a specific trait and then they are termed +as alleles . + Depending on the genes the expression of the traits could be either +dominant or recessive . If we take the t allness in a plant as dominant trait, +then it can be denoted by ‘T’ and shortness in the plant would be a +recessive trait, denoted by ‘t’. Thus the plant will be tall if it’s alleles are +‘TT’ or ‘Tt’. + The condition when the alleles of the genes have the same allele for +a trait, they are termed as homozygous . Example - TT or tt . + The condition when the alleles of the genes have the different alleles +for a trait, they are termed as heterozygous . Example - Tt. + The morphological expression of a single character is termed as +phenotype . Example - tallness or shortness , round or wrinkle d seeds of the +plant.Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +a trait, they are termed as homozygous . Example - TT or tt . + The condition when the alleles of the genes have the different alleles +for a trait, they are termed as heterozygous . Example - Tt. + The morphological expression of a single character is termed as +phenotype . Example - tallness or shortness , round or wrinkle d seeds of the +plant. + The genetic constitution or the allele pair for a specific trait is termed as +the genotype . Example - Tt or t tot TT. + Mendel was a mathematician so; he found the statistics of the traits in each +generation by using a statistical met hod known as Punnett square for +predicting t he possible genotypes and phenotypes of the offspring. + He conducted his experiments to find two types of inheritance namely: + +1) Monohybrid inheritance : + Mendel took a tall (TT) and short (tt) pea plant, crossed it to get the +offspring. The first generation or F1 were all found to be tall , +showing only one of the traits of the parent. + + + 3 + + + Then he self -pollinated the parent and the F1 plants. It was +interesting to see that the offspring of the parent plants were all tall, +but the offspring of the F1 plants, the F2 generation did not have all +tall plants. A quarter of them were short , which indicated that both +traits of the parent was inherited by F1 generation. + The traits of tallness wa s dominant and so it was expressed even with +the genotype of TT, Tt but the shortness was a recessive trait that +could be expressed only with a genotype of tt. + + + + So, the genotype - 1:2:1 And the phenotype - 3:1 + The inheritance of a trait by a pair of single alleles of a gene is termed +as monohybrid inheritance . + + +2) Dihybrid inheritance : + When a pea plant with two different traits; a plant with round green +colour seed (RR yy) is crossed with wrinkled yellow seed ( rrYY) +plant. + The F1 generation turned out to have round yellow seeds , RrYy,Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt + The inheritance of a trait by a pair of single alleles of a gene is termed +as monohybrid inheritance . + + +2) Dihybrid inheritance : + When a pea plant with two different traits; a plant with round green +colour seed (RR yy) is crossed with wrinkled yellow seed ( rrYY) +plant. + The F1 generation turned out to have round yellow seeds , RrYy, +which showed the dominant traits to be round shape and yellow +colour . + + + + 4 + + + When the F1 generation were self -pollinated , the F2 generation had +greater variations than the parent and new combination also came +up. + + + + So, the genotype - 9 different combinations and the phenotype - +9:3:3:1 . + The inheritance of different traits by t wo pairs of alleles for it is +termed as dihybrid inheritance . And here the two traits of +round/wrinkled seeds and green/yellow colour were inherited +independently. + + + 5 + +2.3 How do these traits get expressed? + The DNA present in the cell is responsible for making the proteins. A +section of this DNA that provides information for one protein is termed as +the gene for that specific protein. + The proteins that are thus synthesized are essential in many of the +biochemical reactions that are responsible for the expression of a trait and +they are controlled by specific enzymes. + Any alterations in them will lead to a v ariation in that trait, and hence genes +control the traits in a such a way. If the traits are to be inherited +independently from both the parents, then they need to be present +separately. + Therefore each gene set is present as a separate independent pieces that are +called as chromosomes , with each cell having two sets , one each from +both the parents. + When these two germ cells combine, they tend to restore the number of +chromosomes and hence the DNA. Hence there are two genes for the +expression of every trait . + +2.4 Sex determination :Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +separately. + Therefore each gene set is present as a separate independent pieces that are +called as chromosomes , with each cell having two sets , one each from +both the parents. + When these two germ cells combine, they tend to restore the number of +chromosomes and hence the DNA. Hence there are two genes for the +expression of every trait . + +2.4 Sex determination : + There are various mechanism that determine the sex of a new born +organism. It may be based on the temperature where the fertilised eggs is +kept as in few reptiles, or they may changes ex as in snails. Humans on +the other hand the sex of a new born child is determined predominantly by +the genes inherited from the parents. + All the chromosomes in humans are not paired. There are generally a pair +of 22 chromosomes , with a one of the pair being from each of the p arent. +These generally determine all the traits. + There is a pair of chromosomes known as the sex chromosomes that differ +in males and females. The females have a correct pair and they are termed +as X chromosomes, but men have an X chromosome and its pair as Y. So +the genotype of women is XX and men is XY . + If we look at the inheritance pattern of a male and female, we can see that +X is inherited by the child from their mother by default and the sex of the +child depends on which pair of the sex chromosome is being inherited +from the father . + If it X, then the pair becomes XX and the child is a girl and if Y is inherited, +then it becomes XY and thus the chid is a boy. + + 6 + +3. Evolution: + The process of a gradual development over millions of years in organisms +through generations by inheriting the traits of their previous generations is +termed as evolution . + The evolution eventually leads to the evolvement of new species . +According to J B S Haldane, life on earth may have started as a simpleHeredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt + 6 + +3. Evolution: + The process of a gradual development over millions of years in organisms +through generations by inheriting the traits of their previous generations is +termed as evolution . + The evolution eventually leads to the evolvement of new species . +According to J B S Haldane, life on earth may have started as a simple +organic molecule and has developed into complex organism with the +changing conditions on earth during various periods. + Charles Robert Darwin was an English naturalist who proposed the idea +of “evolution of species by natural selectio n’ although he was not aware +of the mechanisms responsible for the variations. + Natural selection refers to the selection of some traits of a population that +favour their survival making them adapt to the en vironment. + It was Mendel who proposed the mechanism behind the inheritance of +traits. Both these scientist worked on their theories independently. + These traits that are inherited may be acquired also. + +3.1 Acquired and inherited traits: + Any trait that is acquired by an organism during its lifetime due to any +external conditions is not transmitted to its offspring. These traits are +termed as acquired trait . Example - the way a person speaks or the skills +he/she has. These changes do not af fect the germ cells and so they cannot +be passed on from one generation to the other. + + + 7 + Any trait that is genetically inherited or passed down from one generation +to the next generation is termed as inherited trait . Example - the colour of +eyes or skin. + +4. Speciation: + A group of organisms that are similar in their traits and are capable of +breeding within themselves are termed as species . + The mechanism or process by means of which a new or distant species is +formed from the pre -existing species due to v arious factors is termed as +speciation .Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +eyes or skin. + +4. Speciation: + A group of organisms that are similar in their traits and are capable of +breeding within themselves are termed as species . + The mechanism or process by means of which a new or distant species is +formed from the pre -existing species due to v arious factors is termed as +speciation . + This process leads to the formation of different species within a population +that is not capable of reproducing among themselves. + The various factors for the same may be seen as: +1) Splitting of population: + The popul ations tends to grow rapidly when there is a favourable +environment for their survival. As a result the population is very +large and spread out. + This makes it difficult for all the members to interact among +themselves due to the geographical isolation , so they tend to +reproduce with the local near by population. And if they are +separated by any barrier like a mountain or a river, then they are +isolated further . + This will cause the gene flow or transfer of genes in a population +to reduce and they may d evelop into a new or distant species. +2) Genetic drift : + The populations undergoes a change in their genes for some +traits that are specific to that species due to unprecedented +reasons. This leads to them being transferred to another existing +population. + Example - If there are a population of red and green beetles and +the green are eliminated by being in a forest fire, then the +population of only red beetles will remain. +3) Natural selection : + The process by which certain populations are selected over othe rs +due to their variations and ability to adapt is termed as natural +selection . They lead to the formation of new species over a period +of time. + Example - In case of a storm, the birds with long or short wings +died as compared to the ones with average wings. So, they were + + 8Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt + The process by which certain populations are selected over othe rs +due to their variations and ability to adapt is termed as natural +selection . They lead to the formation of new species over a period +of time. + Example - In case of a storm, the birds with long or short wings +died as compared to the ones with average wings. So, they were + + 8 +naturally selected to adapt to that environment changes and they +survive to evolve their species. + The process of genetic drift and natural selection will eventually lead to two +isolated sub species that are entirely different from eac h other and they form +a new species altogether and thus speciation occurs. + +5. Evolution and Classification: + Every species goes through a phase of evolution. The similarities among +organisms that allow them to be grouped are based on the characteristics +or the details of the appearance or behaviour that is seen for a particular +form or a function. + There are some basic characteristics that are shared by most of the +organisms like, the cell being the fundamental unit of life. But the next +level of grouping or classification may not be common for all the +organisms, like the cell may have a nucleus or not. This classification goes +further as whether the nucleated cells are single celled or multicellular. +This allows a hierarchy to be created in the evolution process that helps +us in the classification of groups . + Thus the more common characteristics are shared by two species, the more +closely related they are. The more closely they are related, indicates that +they have had common ancestors recently. Example - In a family, a brother +and a sister are closely related with common ancestors as parents . Now the +girl and her cousin too are related as they common ancestors, grandparents. +But they are distant than her brother as they common ancestors in second +generati on.Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +closely related they are. The more closely they are related, indicates that +they have had common ancestors recently. Example - In a family, a brother +and a sister are closely related with common ancestors as parents . Now the +girl and her cousin too are related as they common ancestors, grandparents. +But they are distant than her brother as they common ancestors in second +generati on. + Thus small group of species with recent common ancestors are built, +followed by distant common ancestors and this goes on backwards in the +evolutionary process. + +5.1 Tracing Evolutionary relationships: + In the evolutionary relationships, the occurrence of common c haracteristics +are the basis of classifying them into groups. These common characteristics +can be identified as being of 2 types, na mely : +1) Homologous characteristics : These are those characteristics that +are present in different organ ism but look similar and they have a +have a common ancestor . They may have the similar basic organ +structures but with a different function in various organisms. +Example - Mammals, birds, reptiles and amphibians have four +limbs , but each serves a different purpose and are modified to +perform that function. + + 9 +2) Analogous characteristics : These are those characteristics that +have the similar function in different organisms and they have +evolved independently for different ancestors . Example - the +wings of bats and of birds look similar as they serve to perform the +same function of flying, but the wings of a bat are actually a fold of +skin between the fingers. + Hence these different types of characteristics help in tracing the +evolutio nary relationships between species to a great extent. + +5.2 Fossils: + To study the evolutionary relationships, the current species as well as the +species that are no longer in existence also needs to be considered.Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +skin between the fingers. + Hence these different types of characteristics help in tracing the +evolutio nary relationships between species to a great extent. + +5.2 Fossils: + To study the evolutionary relationships, the current species as well as the +species that are no longer in existence also needs to be considered. + The body of an organism usually decomposes when it dies, but due to some +environmental conditions like hot mud or lava, their bodies may be buried +in them, harden and eventually leave an impression o f the body parts. This +preserved traces of the living organisms that existed in a past ge ological +period are termed as fossils. + The fossils help in determining the various evolutionary stages of the +species. The process of conversion of an organism into a fossil is termed +as fossilisation and its study is referred to as palaeontology. + There a re two ways to determine the age or dating of the fossils. +1) Relative dating: This method involves the digging of the earth and +excavating the fossils from the rocks. The more recent ones are +found closer to the earth’s surface. +2) Radiometric dating: In this method, the fossils can be dated based +on the radioactive elements present in the rocks and detecting the +ratios of different isotopes of the same element in the material of the +fossil . + +5.3 Evolution by Stages: + It is well established that e volution is a gradual process that takes place +over thousands of years. The complex organs that have evolved in +organisms is not due to a single DNA change but due to thousands of such +changes over a large period of time. If the eyes of an octopus and the +vertebrates are considered then it is different in both of them suggesting +that they have evolved independently. It is also to be noted that a change +brought on for a particular feature may have later evolved into a different +function alto gether. For example, the purpose of feathers initially wasHeredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +changes over a large period of time. If the eyes of an octopus and the +vertebrates are considered then it is different in both of them suggesting +that they have evolved independently. It is also to be noted that a change +brought on for a particular feature may have later evolved into a different +function alto gether. For example, the purpose of feathers initially was +considered to provide insulation in cold weather and this is seen in some +of the reptiles like the dinosaur , who could not fly. In the evolutionary + + 10 +process birds adapted these feathers for flight. This leads to the belief that +birds were closely related to reptiles. + Similarly some structures that are dissimilar have evolved from common +ancestors. The best example of it would be wild cabbage that humans have +used as food for over two thousand years. They generated different types +of vegetables out of the would cabbage by artificial selection and +developed the cabbage with short leaves, broccoli which is arrested +flowers, cauliflower, the swollen parts as kohlrabi, or leafy kale. If not for +artificial selection in this, it would not be known that they originated from +a common ancestor . + The change in the DNA is yet another way to understand the ev olutionary +relationships . The comparison of the DNAs of different species would +give an insight into the changes that have happened in their evolutionary +process. + +6. Evolution should not be equated with progress : + The evolution of a new species does not indicate that the old species has +been eliminated or they are inefficient than the new one. It indicates that +the new species have evolved as a result of changing environmental +conditions. + It can be said that evolution is a process of creating diversity of species +due t o natural selection and genetic drift . This creates a population that isHeredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt + The evolution of a new species does not indicate that the old species has +been eliminated or they are inefficient than the new one. It indicates that +the new species have evolved as a result of changing environmental +conditions. + It can be said that evolution is a process of creating diversity of species +due t o natural selection and genetic drift . This creates a population that is +not capable of reproducing with the original species. For example, humans +and chimpanzees may have had common ancestors and with time they have +evolved in separate directions leading to the present species. + Hence there is no progress that can be mapped during evolution. Each and +every species diversifies in order to reproduce and survive and adapts itself +accordingly. + The on ly factor is that more and more complex organs have developed in +the evolutionary process. That does not indicate the simplest older species +like the bacteria are extinct. They can survive in diverse conditions of hot +springs, Antarctica etc. Humans are th e most evolved, but they are just +another species in the evolutionary process. + +6.1 Human Evolution: + The evolutionary relationship in humans ha s also been traced by the +various methods of excavation, time -dating, studying the fossils, and DNA +sequences . A great diversity exists among the people of the world in their +features, colours, etc. Many times , groups of humans were grouped based +on their skin colour. But there is no biological reason for that as all the + + 11 +humans are part of a single same species. Eve ryone belongs to the species +- Homo sapiens . + A large number of genes are present in this gene pool which is the source +of the vast variations found in humans. This is the reason that no two +individuals are alike in looks, abilities, etc, that leads to the diversity in +skin colour, height, hair colour, etc.Heredity and Evolution CBSE class 10 Notes CBSE Science Chapter 9 (PDF).txt +humans are part of a single same species. Eve ryone belongs to the species +- Homo sapiens . + A large number of genes are present in this gene pool which is the source +of the vast variations found in humans. This is the reason that no two +individuals are alike in looks, abilities, etc, that leads to the diversity in +skin colour, height, hair colour, etc. + Though the humans inhabit different parts of the modern world, all of them +originated from Africa . The original inhabitants of Africa migrated to +across to West Asia, central Asia, Eurasia etc and all this while they were +travelling back to Africa too. This lead to a diverse gene pool in a staggered +manner as the population across the world increased.Our Environment CBSE class 10 Notes CBSE Science Chapter 15 PDF.txt + 1 +Revision Notes +Class – 10 Science +Chapter 15 - Our Environment + +1. What happens to the environment when we add waste to it. +The environment of an organism refers to the physical and biological conditions in +which the organism lives. The physical conditions consist of various factors like soil, +temperature, light, etc. Whereas the biological conditions include the plants, +anima ls, and microorganisms around it. A slight change in any of these conditions +can affect the organism. +When the waste generated is added to the environment it disturbs the ecological +balance. The wastes are broadly classified into two categories: - +Substanc es that can be broken down by biological processes are known as +biodegradable. On the other hand, substances that can not be broken down by +biological processes are known as non -biodegradable. These substances can be inert +and remain in the environment for a very long time causing harm to the various +members of the ecosystem. + +2. What are the components of the ecosystem? +All organisms including plants, animals, microorganisms, and human beings interact +with the physical surroundings as well as with each oth er to maintain balance in our +environment. +An ecosystem is a community of organisms with their physical environment +interacting with each other as an ecological unit, leading to the flow of energy. An +ecosystem is made up of biotic components which include living organisms and +abiotic components which include physical factors like temperature, rainfall, wind, +soil, and minerals. +An ecosystem can be of two types: +Natural : - Ponds, forests, and lakes are natural ecosystemsOur Environment CBSE class 10 Notes CBSE Science Chapter 15 PDF.txt +interacting with each other as an ecological unit, leading to the flow of energy. An +ecosystem is made up of biotic components which include living organisms and +abiotic components which include physical factors like temperature, rainfall, wind, +soil, and minerals. +An ecosystem can be of two types: +Natural : - Ponds, forests, and lakes are natural ecosystems + + 2 +Artificial: - garden and crop field s are man -made +In both of the above ecosystems, all living organisms interact with each other and +their growth, reproduction, and some of the other activities are affected by the abiotic +components of the ecosystem. +Organisms present in the ecosystem can be further categorized into producers, +consumers, and decomposers in accordance with the manner in which they obtain +their nutrition from the environment. +Producers are organisms that are capable of producing their own food without the +help of any other o rganism. They are also called autotrophs. They synthesize their +food from inorganic substances by a process called photosynthesis. Autotrophs are +the green plants, phytoplankton, and blue -green algae. +Consumers are the organisms that do not produce food bu t depend directly or +indirectly on producers for their food needs. These are called heterotrophs. +Consumers can be further classified into herbivores, carnivores, omnivores, and +parasites. For example Humans, snakes. Decomposers are the organisms that feed +on dead and decaying matter and break down the complex organic substances into +the simple inorganic substances. These simpler substances go into the soil and are +used up again by the plants. Eg: Bacteria and fungi. + +2.1 Food chains and Webs: +The series of organisms that are taking part at various biotic levels constitute a foodOur Environment CBSE class 10 Notes CBSE Science Chapter 15 PDF.txt +on dead and decaying matter and break down the complex organic substances into +the simple inorganic substances. These simpler substances go into the soil and are +used up again by the plants. Eg: Bacteria and fungi. + +2.1 Food chains and Webs: +The series of organisms that are taking part at various biotic levels constitute a food +chain. Food chains signify the feeding relationship between the organisms in an +ecosystem. In the food chain, the flow of energy from one species to another occurs. +Every food chain always begins with producers. + The successive levels present in the food chains of a community are known as +trophic levels. From autotrophs, the energy is passed to the heterotrophs and +decomposers. When this energy is transferred from one le vel to the other level, some +of the energy is lost to the environment in forms that cannot be used again. A +common example of food chains are: - +Plants → Deer → Lion + + + 3 +The food chain consists of up to three or four trophic levels. Since the loss of energy +at every step is so huge that a very small amount of usable energy remains when it +reaches the fourth trophic level. The number of individuals at the lower trophic levels +of an ecosystem is generally more therefore the largest number is of the producers. +The length and complexity of food chains differ. Every organism is in general eaten +by two or more other kinds of organisms which in turn are eaten by several other +organisms belonging to a higher level. This relationship between organisms can be +shown by a series of branching lines known as food web. Many cross -linked food +chains constitute the food web. +The flow of energy between the trophic levels in any ecosystem is unidirectional. +The energy that is captured by the autotrophs is passed to the higher tro phic levelsOur Environment CBSE class 10 Notes CBSE Science Chapter 15 PDF.txt +organisms belonging to a higher level. This relationship between organisms can be +shown by a series of branching lines known as food web. Many cross -linked food +chains constitute the food web. +The flow of energy between the trophic levels in any ecosystem is unidirectional. +The energy that is captured by the autotrophs is passed to the higher tro phic levels +and energy does not revert back to the lower level. Some of the harmful chemicals +enter our bodies through the food chain. For example use of several pesticides and +other chemicals to protect the crops from diseases and pests runoff with water in the +field which are taken up by the fishes entering in the food chain. +Biological magnification is a phenomenon by which harmful substances or +chemicals accumulate from the lower trophic level to a higher one. As human beings +are at the top level in an y food chain, so the maximum concentration of these harmful +chemicals gets accumulated in the body which can cause death of the person. + +3. How does the environment affect our activities? +3.1 Ozone layer and its depletion. +Ozone molecule consists of three oxygen atoms. The ozone layer is present in the +upper layer of the atmosphere i.e. stratosphere. It is a very deadly poison. It is +responsible for causing skin cancer in human beings. Whereas, at the higher levels +of the at mosphere, it protects us from harmful UV radiations of the sun which is +dangerous to living organisms. Ozone depletion is the marked reduction of ozone +molecules in the stratosphere due to chlorofluorocarbons (CFCs) used in refrigerants +and other coolants. Oxygen in the presence of ultraviolet rays gets broken down to +nascent oxygen molecules. This nascent oxygen further reacts with the oxygen +present in the atmosphere and forms ozone molecule. + + + 4Our Environment CBSE class 10 Notes CBSE Science Chapter 15 PDF.txt +and other coolants. Oxygen in the presence of ultraviolet rays gets broken down to +nascent oxygen molecules. This nascent oxygen further reacts with the oxygen +present in the atmosphere and forms ozone molecule. + + + 4 +In order to limit the damage to the ozone layer the release o f CFC s into the +atmosphere needs to be reduced instead alternatives should be used. + +3.2 Managing the garbage produced: +Improvements in the lifestyle have to lead to greater amounts of waste material +generation. Changes in the packaging of items have resu lted in huge amount of waste +becoming non -biodegradable. Increased use of non -biodegradable items has left the +environment polluted with them. In order to manage this waste we can do following: - +1. Use of concept of 3R's (reduce, reuse and recycle). +2. Sep eration of biodegradable and non -biodegradable waste.Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt + 1 + + +Revision Notes +Class 10 Science +Chapter 12 - Electricity + +Introduction +● The Greek words " Electrica " and " Elektron " were used to describe +electricity . +● Thales, a Greek philosopher , was the first to notice how certain elements +attract other materials when rubbed together. +● These materials were divided into two categories by Gilbert: vitreous and +resinous , as Positive charges and Negative charges . + +Frictional Electricity +● Fur, flannel, wax, glass, cotton, paper, silk, human skin, wood, metals, rubber, +resin, amber, sulphur, and ebonite are just a few of the materials used. +● If any two materials in this series are rubbed together, the element that occurs +initially in the series will get positiv e charge, while the element that occurs +later in the series will gain negative charge. + +Fundamental Laws of Electrostatics +● Positive and negative charges are the two types of charges. +● Charges that are similar repel each other, while charges that are dissimilar +attract each other. + +Coulomb’s Law +● + qq12F 2r +● The electrostatic attraction or repulsion force between two charges is +proportional to the product of their charges and inversely proportional to +the square of their distance. +● + Kq q12F = 2r +● +K is the constant of proportionality and is equal to +9 2 29×10 Nm /C for free +space. +● The force is repulsive for similar charges and attracting for dissimilar ones. + +Charge Conservation + + 2 + + +● When an ebonite rod is brushed with fur, the ebonite gains a negative charge , +while the fur gains a positive charge . +● This indicates that electrons have transferred from fur to ebonite. +● The system's net charge stays unchanged. +● As a result, charges are not genera ted or destroyed; rather, they are moved +from one material to another. + +Insulators and ConductorsElectricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +● When an ebonite rod is brushed with fur, the ebonite gains a negative charge , +while the fur gains a positive charge . +● This indicates that electrons have transferred from fur to ebonite. +● The system's net charge stays unchanged. +● As a result, charges are not genera ted or destroyed; rather, they are moved +from one material to another. + +Insulators and Conductors +● Insulators are poor conductors of electricity , yet they can be quickly charged +through friction. +● Charges can flow freely through conductors.. + +Current +● The rate of charge flow is referred to as current. +● If the charge +q is in coulomb and +t is the time is seconds then, + current is + +qI = t +● The +SI unit of current is ampere +��A . +● Current is a scalar quantity . +● Example: +A current of +1A is drawn by a filament of an electric bulb for +20 +minutes. Find the amount of electric charge that flows through the +circuit. +Ans: +The given data is, +I = 1A + and +t = 20 minutes + +t = 20 60 + +t = 1200 seconds + +Therefore, +qI = t + +Electric charge is +q = It + +q = 1×1200 + +q = 1200 C + +Symbols used in electric circuit + + + 3 + + +Electric +Component Function/ Description Symbol + + +Connecting Wire A straight line represents a +connecting wire . +It's commonly constructed of +copper and has insulation on +both ends to link two places +electrically. + + + + + + +Resistor A zip zap line is used to depict +the resistor . +Brass terminals are represented +by two heavy dots at the ends , +to which a wire is attached. +Alloys like as nichrome, +manganin, constantan , and +eureka are commonly used to +make resistor wire. + + + + + + + +Cell The positive terminal of a cell is +represented by a thin long line , +while the negative terminal is +represented by a thick and short +line. +Electrical current source . + + + +Fuse In an electric circuit , to limit the +current.Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +Alloys like as nichrome, +manganin, constantan , and +eureka are commonly used to +make resistor wire. + + + + + + + +Cell The positive terminal of a cell is +represented by a thin long line , +while the negative terminal is +represented by a thick and short +line. +Electrical current source . + + + +Fuse In an electric circuit , to limit the +current. + + + + +Plug key To build or break an electric +circuit for an extended period of +time. + + + + +Battery A cell that is made up of two or +more cells. +The cells are placed in a row +here. +Electrical current source. + + + + + + 4 + + + + +Electric bulb When voltage is placed across +the terminals of an electric +device, such as an incandescent +lamp, glow lamp, or fluorescent +lamp, it creates light. + + + +Connecting +wires Wires are linked together. + + + +Connecting +wires Crossing wires that aren't +linked. + + + + + +Voltmeter It's a device that measures the +difference in potential between +two locations in an electric +circuit. + + + + +Ammeter It's a tool for determining +current in an electric circuit. + + + + +Alternating +current Alternating current is a type of +current that changes direction +fast on its own. + + + + + + + 5 + + + + +A circuit diagram is a diagram that displays how different components in a circuit +have been connected using traditional component symbols. + +Electrical Potential +● Electric potential is the work done in carrying a unit positive charge from +infinity to a point. +● If +W is the work done +q is the charge, then electric potential + +WV = q +● The +SI unit of electric potential is Volts +V + +Electric Potential Difference +● The work done required to move a unit charge from one location to the other +is defined as the electric potential difference between two points in an electric +circuit carrying some current.Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +infinity to a point. +● If +W is the work done +q is the charge, then electric potential + +WV = q +● The +SI unit of electric potential is Volts +V + +Electric Potential Difference +● The work done required to move a unit charge from one location to the other +is defined as the electric potential difference between two points in an electric +circuit carrying some current. + + +Work done WPotential difference V between two point s = Charge Q +● The electric potential difference between points +A and +B is, + +ABWork done to carry charge q from A to BV = Charge Q +● The +SI unit of electric potential difference is Volts +V . +● Example: +How much work is done in moving a charge of +4 C across two points +having a potential difference +24 V ? +Ans: +Given data is, +Charge, +Q = 4 C +Potential difference, +V = 24 V + + + 6 + + +Therefore, the amount of work +W done in moving the charge can be calculated +as, +W = V×Q + +W = 24 4 + +W = 96 J + + +Electric Potential energy +● The work done required to transport charges to their proper places against the +electric field using a source of energy is known as electric potential energy . +● The potential energy of the charges is used to store the work done. + +Ohm’s Law +● Under similar physical conditions, the current flowing through a wire is +directly proportional to the difference in potential applied across its ends. + +V I + +V = ConstantI + +V = RI + Therefore, + +V = IR + Where +R is the resistance offered. + + + + +Resistance + + + 7 + + +● Resistance is the opposition to the flow of current. +● The +SI unit of resistance is Ohm + . +● +1 Ohm is the resistance offered by a wire carrying +1 A current when +1 V is +applied across its ends. +● +VR = I + +1 Volt1 Ohm = 1 AmpereElectricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +V = IR + Where +R is the resistance offered. + + + + +Resistance + + + 7 + + +● Resistance is the opposition to the flow of current. +● The +SI unit of resistance is Ohm + . +● +1 Ohm is the resistance offered by a wire carrying +1 A current when +1 V is +applied across its ends. +● +VR = I + +1 Volt1 Ohm = 1 Ampere +● Variable resistance is a component that regulates current without changing +the voltage source . +● A rheostat is a device that is commonly used to adjust the resistance in an +electric circuit. + +Factors Affecting Resistance +● A conducting wire's resistance is determined by: +1. Nature of the material of the wire + ) Resistiv ty ( Ωi +2. Length of the wire +l +3. Cross -sectional area of the wire +A +● Resistance is directly proportional to its length +l and inversely proportional +to the area of cross -section +A . + That is, + +R α l +1R α A + +Therefore, +lR α A + +lR = A + +Where, + ρ rho + is a proportionality constant that refers to the electrical resistivity +of the conductor's substance. + +Resistivity +● The resistance offered by a wire of unit length and unit cross -sectional area is +called resistivity. +● Resistivity is also known as specific resistance . +● +m ohm-meter is the +SI unit for resistivity. + + 8 + + +● Metals and alloys have very low resistivity which in the range of +8610 m to 10 m + . +● The resistivity of insulators such as rubber and glass is on the order of +12 1710 m to 10 m +. +● Temperature affects both a material's resistance and its resistivity. +● An alloy's resistivity is usually higher than that of its constituent metals. +● At high temperatures, alloys do not easily oxidise (burn) and hence, they're +frequently used in electrical heating devices like electric irons and toasters.Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +12 1710 m to 10 m +. +● Temperature affects both a material's resistance and its resistivity. +● An alloy's resistivity is usually higher than that of its constituent metals. +● At high temperatures, alloys do not easily oxidise (burn) and hence, they're +frequently used in electrical heating devices like electric irons and toasters. +● Tungsten is nearly exclusively utilised in electric bulb fila ments, while copper +and aluminium are commonly used in electrical transmission lines. +● Reciprocal of resistivity is called conductivity . +● Conductivity can be calculated as; + +l = Ω + +● +SI unit of conductivity is +-1 -1ohm m or +-1mho-m + +Effect of Temperature +● A conductor's resistance increases linearly as the temperature rises. +● As the temperature rises, an insulator's resistance rises as well. +● As a semiconductor's temperature rises, its resistivity falls. +● The resistivity of an alloy increases as the temperature rises. + +Semiconductors and Superconductors + Semiconductors are materials with resistivity that fall between those of an +insulator and a conductor. + Materials which lose their resistivity at low temperatures are called super +conductors. + +Examples: +i. The potential difference between the terminals of an electric heater is +45 V + when it draws a current of +3 A from the source. What current will +the heater draw if the potential difference is increased to +120 V ? +Ans: +Given data is, +Potential difference +V = 45 V and current +I = 3 A +According to Ohm’s law, +VR = I + +45R = 3 + + + 9 + + +R = 15  +When the potential difference is increased to +120 V the current is +given by +VI = R + +120I = 15 + +I = 8 A + +As a result, the heater's current becomes +8 A . + +ii. A wire of given material having length +l and area of cross -section +A has a +resistance of +8  . What would be the resistance of another wire of the +same material having length +lElectricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +R = 15  +When the potential difference is increased to +120 V the current is +given by +VI = R + +120I = 15 + +I = 8 A + +As a result, the heater's current becomes +8 A . + +ii. A wire of given material having length +l and area of cross -section +A has a +resistance of +8  . What would be the resistance of another wire of the +same material having length +l +4 and area of cross -section +2A ? +Ans: +For first wire, resistance is; +1lR = ρ = 8ΩA + +Now, for the second wire, resistance is +2l +4R = ρ 2A + +21 +4R2A + +Since, +ll = 4 +Therefore, +2lR = ρ8A + +21lR = R8 + +Since, +1R8 +Therefore, +2R becomes +2lR = 88 + +2R1 + +As a result, the new wire's resistance is +1 + + + 10 + + +Resistances in Series + The sum of the individual resistances of multiple resistors in series equals their +equivalent resistance. + If resistances +12R , R and +3R are connected in series , then the equivalent +resistance can be calculated as, + +s 1 2 3R = R R R + When numerous resistors are connected in series, the combined resistance +sR +equals the total of their individual resistances +1 2 3R , R ,R and hence, +sR is +greater than any individual resistance. + In series circuit, current remains the same and potential difference vary . + + + The current in a series circuit is constant throughout the electric circuit. As a +result, connecting an electric lamp and an electric heater in series is clearly +impractical, as they require currents of vastly different values to function +effectively. + The main disadvantage of a series circuit is that if one component fails, the +circuit is broken and none of the other components works. +● Example: +An electric lamp, whose resistance is +25  , and a conductor of +5  +resistance are connected to a +9 V battery as shown in below figure. Calculate +a. The total resistance of the circuit, +b. The current through the circuit.Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt + The main disadvantage of a series circuit is that if one component fails, the +circuit is broken and none of the other components works. +● Example: +An electric lamp, whose resistance is +25  , and a conductor of +5  +resistance are connected to a +9 V battery as shown in below figure. Calculate +a. The total resistance of the circuit, +b. The current through the circuit. + + + 11 + + + + +Ans: +The resistance of electric lamp, +1R = 25  + +The resistance is connected in series, +2R = 5  + +Then the total resistance in the circuit can be calculated as, +s 1 2R = R R + +sR = 25 5 + +sR = 30  + +The overall difference in potential across th e battery is +V = 9 V + +According to Ohm’s law, the current through the circuit can be calculated as; +sVI = R + +9I = 30 + +I = 0.3 A + + +Resistances in Parallel + If resistances +12R , R and +3R are connected in parallel, then the equivalent +resistance +pR is given by + +p 1 2 31 1 1 1 = + +R R R R + The sum of the reciprocals of the individual resistances is equal to the +reciprocal of the equivalent resistance of a group of resistances linked in +parallel. + + + 12 + + + In parallel circuit, potential difference remains the same and current will +be vary . + The current flowing through the electrical devices is divided in a parallel +circu it. + This is especially useful when each device has a different resistance and +requires a varied amount of current to function properly. + + + + Example: +In the circuit diagram given in below figure, suppose the resistors +12R , R +and +3R have the values +2 ,4 ,6 respectively, which have been connected +to a battery of +9 V . +Calculate +a. The current through each resistor, +b. The total current in the circuit, and +c. The total circuit resistance. + + +Ans: +Given that + + + 13Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +In the circuit diagram given in below figure, suppose the resistors +12R , R +and +3R have the values +2 ,4 ,6 respectively, which have been connected +to a battery of +9 V . +Calculate +a. The current through each resistor, +b. The total current in the circuit, and +c. The total circuit resistance. + + +Ans: +Given that + + + 13 + + +1R = 2  +2R = 4  + +3R = 6  + +The total potential difference across the battery is +V = 9 V + +According to Ohm’s law, +The current +1I , through +1R +1V= R +1 +1VI = R + +19I = A2 + +1I = 4.5 A + +The current +2I , through +2R +2V= R +2 +2VI = R + +29I = A4 + +2I = 2.25 A + +The current +3I , through +3R +3V= R +3 +3VI = R + +39I = A6 + +3I = 1.5 A + +Therefore, the total current in the circuit can be calculated as; +1 2 3I = I I I + +I = 4.5 2.25 1.5 + +I = 8.25 A + +The total resistance +pR can be calculated as; +p 1 2 31 1 1 1 = + +R R R R + +p1 1 1 1 = + +R 2 4 6 + + + 14 + + +p1 11 = R 12 +Therefore, +p12R = Ω11 + + +Heating Effect of Electric Current + The source energy is constantly dissipated fully in the form of heat if the +electric circuit is purely resistive, that is, a configuration of resistors +exclusively connected to a battery, this effect is called as t he heating effect of +electric current . + Electric heaters, electric irons, and other gadgets are operating on this effect. + For a steady current +I , the amount of heat +H produced in time +t can be +calculated as; + +H = VIt + Joule’s Law of Heating: + When a current +I flows through a resistor +R heat is produced and this +phenomena is called as Joule’s law of heating . + +2H = I Rt + Example: +120 J + of heat is produced each second in a +6  resistance. Find the +potential difference across the resistor. +Ans: +Given data is +H = 120 J + +R = 6  + +t = 1 sec + +According to Joule’s Law of Heating effect,Electricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +When a current +I flows through a resistor +R heat is produced and this +phenomena is called as Joule’s law of heating . + +2H = I Rt + Example: +120 J + of heat is produced each second in a +6  resistance. Find the +potential difference across the resistor. +Ans: +Given data is +H = 120 J + +R = 6  + +t = 1 sec + +According to Joule’s Law of Heating effect, +2H = I Rt + +Therefore, +HI = Rt + +120I = 61 + +I = 20 + +I = 4.47 A + +Thus the potential difference across the resistor +V can be calculated as; +V = IR + + + 15 + + +V = 4.47 6 +V = 26.82 V + + +Applications of Heating Effect of Electric Current + Heat creation in a conductor is an unavoidable result of electric current. + Heat is undesirable because it converts useful electrical energy into heat. + The electric laundry iron, electric toaster, electric oven, electric kettle, and +electric heater are all examples which are working on Joule’s heating effect. + As in an electric bulb, electric heating is also employed to produce light. + Bulb filaments are ma de of tungsten, a strong metal with a high melting point. + The fuse used in electric circuits is another prominent application of Joule's +heating. + +Fuse Wire: + A fuse wire is a wire that melts, breaks the circuit, and protects various +appliances in household connections from damage. + It protects circuits and appliances by interrupting any too high electric current +flow. + The fuse is connected to the device in series. + It consi sts of a piece of wire made of a metal or an alloy with the proper melting +point, as well as a piece of wire made of a metal or an alloy with the appropriate +melting point. + Aluminium, copper, iron , and lead alloys are used to make fuse wires. + The maximum s afe current that can pass through the fuse wire increases +as the thickness of the wire increases. + +Electrical EnergyElectricity CBSE class 10 Notes CBSE Science Chapter 12 [PDF].txt +point, as well as a piece of wire made of a metal or an alloy with the appropriate +melting point. + Aluminium, copper, iron , and lead alloys are used to make fuse wires. + The maximum s afe current that can pass through the fuse wire increases +as the thickness of the wire increases. + +Electrical Energy +● Because of the existence of resistance to the flow of current work has to be +done in order to maintain the flow of current. +● Since the poten tial difference +V is the work done to carry unit positive charge +from infinity to a point, the work done to carry a charge +q is given by: + +W = qV +But +qI = t +Therefore, +W = ItV + +Since +V=IR +Therefore, + + 16 + + +2W = I Rt + +2VtW = R +● This work done is stored as energy. +● +SI unit of electrical energy is Joule . + +Electric Power +● The rate at which electric energy is consumed is called electric power. +● +Work donePower  = Time +WP = t + +2P = V × I R + +2P = V R + +P = VI + +● +SI unit of electric power is Watt . +● Example: +An electric bulb is connected to a +230 V generator. The current is +0.75 A . +What is the power of the bulb ? +Ans: +We have +V = 230 V + +I = 0.75 A + +Thus, Power can be calculated as; +P = VI + +P = 230 0.75 + +Therefore, +P = 172.5 W + + +Calculation of Power for House Hold Electricity +● The commercial unit for electrical energy is the kilowatt hour + kWh +1kWh = 3,600,000 J + +61kWh 3.6 10 J + +● No. of units of electricity consumed in a household can be calculated as; +No. of units of electricity consumed in a household = No. of kWh + +● +Total cost of electricity  = Total units × Cost per unit of electricityPeriodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt + 1 +Revision Notes +Class 10 Science +Chapter 5 - Periodic Classification of Elements + +Introduction: +● In the beginning, scientists had classified elements into two broad +categories as metals and non -metals . Some elements exhibited properties +because of which they could neither be classified as metals nor non -metals +and hence were called metalloids . This classification was not sufficient +for scientific study. Over the years, many chemist s attempted to make a +rational and systematic classification. It was based on the physical and +chemical properties of each element. These results were then tabulated in +the form of a table. +● Periodic table – The table giving the arrangement of the known el ements +according to their properties so that similar elements fall within the same +vertical column and dissimilar elements are separated. + +Dobereiner's Triads: +● In 1817, a German chemist named Johann Wolfgang Dobereiner arranged +the elements with similar properties into groups. +● He identified many such groups which had three elements in them. +Hence, these groups were termed as triads . +● In a triad, the elements were arranged in increasing order of their atomic +masses. When the arithmetic mean of the atomic mass of the first and the +third element was taken, it came out to be approximately the same as that +of the second or the middle elemen t. This is a distinctive feature that can +be used to identify if elements form a triad. +● This classification was also not sufficient as not many triads could be +identified. Only three were identified as: + + 2 + + +Newlands' Law of Octaves: +● In 1866, an English scie ntist, John Newlands arranged many of the then +known elements in the increasing order of their atomic masses. So, he +started with the element having the lowest atomic mass (hydrogen) and +ended at Thorium which was thePeriodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +identified. Only three were identified as: + + 2 + + +Newlands' Law of Octaves: +● In 1866, an English scie ntist, John Newlands arranged many of the then +known elements in the increasing order of their atomic masses. So, he +started with the element having the lowest atomic mass (hydrogen) and +ended at Thorium which was the +th56 element. He noticed that the eighth +element was similar in properties to the first element . +● It was concluded that there exists some systematic relationship between +the order of atomic masses and the repetition of properties of elements. +This relationship, when repres ented in a tabular form, presented a periodic +repetition of the properties of the elements. Hence, the term periodicity +was introduced. +● This had a resemblance to the eight musical notes in both Western as well +as Indian music. + + +● It was found that the Law of Octaves was applicable only up to Calcium +because after Calcium, every eighth element did not possess properties +similar to that of the first. John Newlands had assumed that only 56 + + + 3 +elements existed in nature and no more elemen ts would be discovered in +the future. But several new elements were discovered later on, whose +properties did not fit into the Law of Octaves. So, this was not sufficient +either. + +Mendeleev's Periodic Table: +● In 1869, a Russian chemist, Dmitri Ivanovich Men deleev classified the +then known 63 elements based on their physical and chemical properties +in the increasing order of the atomic masses in the form of a table. +● He had observed that properties of the elements recur cyclically when they +were arranged in th e order of their increasing atomic masses. This +observation led to the conclusion that the physical and chemical properties +of the elements are periodic functions of their atomic masses. This came +to be known as the law of chemical periodicity .Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +● He had observed that properties of the elements recur cyclically when they +were arranged in th e order of their increasing atomic masses. This +observation led to the conclusion that the physical and chemical properties +of the elements are periodic functions of their atomic masses. This came +to be known as the law of chemical periodicity . +● Periodic Ta ble is the tabulation of all the known elements in a tablular +format based on this law. It contains eight vertical columns called +'groups' and seven horizontal rows called 'periods' . Each of the eight +groups has two sub -groups A and B. The properties of el ements of a sub - +group resemble each other more markedly than the properties of those +between the elements of the two sub -groups. + +Achievements of Mendeleev's Periodic Table: +Some of the important contributions of Mendeleev's periodic table are as +follows: +1) Systematic Study of Elements – The table provided the arrangements of +elements showing similar properties into groups. This was very useful in +studying and remembering the properties of a large number of elements in +a systematic way. +2) Prediction of New Elem ents – Mendeleev had predicted new elements +and had left three blanks for these undiscovered elements. He was able to +predict their properties more or less accurately. He named them eka - +boron, eka -aluminium and eka -silicon. +3) Correction of Atomic Masses - Based on the elements’ positions in the +periodic table, Mendeleev was able to correct their atomic masses. The +atomic mass of beryllium was corrected from 13.5 to 9.0. + +Limitations of Mendeleev’s classification: +Although Mendeleev's periodic table has many advantages, it could not explain +certain things, which are considered as its limitations. They are as follows: + + 4 +1) Assigning a position to Hydrogen: Hydrogen has a electronic +configuration as that of alkali metals a nd combines with halogens, oxygen,Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +Limitations of Mendeleev’s classification: +Although Mendeleev's periodic table has many advantages, it could not explain +certain things, which are considered as its limitations. They are as follows: + + 4 +1) Assigning a position to Hydrogen: Hydrogen has a electronic +configuration as that of alkali metals a nd combines with halogens, oxygen, +sulphur to form compounds, like +22 HCL,H O,H S and at the same time it +exists as a diatomic molecule like halogens. So, Mendeleev was not able +to assign a proper position for hydrogen. +2) Assigning position to isotopes: The isotopes have similar properties but +differ in their atomic masses. Mendeleev’s classification would place +them in different groups due to their different atomic masses, but isotopes +were not placed so as their propertie s were similar. +3) Anomalous pairing of some elements: Mendeleev did not follow the +increasing atomic masses but grouped some elements based on similar +properties. Argon with an atomic mass of 39.9 was placed before +potassium with atomic mass of 39.1. Also s ome elements with similar +properties like copper (Cu) and mercury (Hg) were placed separately, and +some very dissimilar elements were placed in one group. Copper was +placed in group I, the elements of which had no similarities with copper. + +The Modern Periodic Table: +● In the year 1913, an English physicist named Henry Mosely found that +the atomic number of an element, which was denoted by symbol ‘Z’ was +a more basic property to group them instead of their atomic masses. Thus +Mendeleev's period ic table was modified for the same. The elements were +now grouped based on the increasing atomic number. +● This came to be known as the Modern Periodic Law and it states, +‘properties of the elements are a periodic function of their atomic number’. +Hence the new classification of the elements based on this came intoPeriodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +Mendeleev's period ic table was modified for the same. The elements were +now grouped based on the increasing atomic number. +● This came to be known as the Modern Periodic Law and it states, +‘properties of the elements are a periodic function of their atomic number’. +Hence the new classification of the elements based on this came into +existence and was termed as ‘ Modern Periodic Table’ . +● With this system of grouping it was easy to predict the properties of the +elements when they were arranged in the order of increasing atomic +numbers. It is to be noted that the periodicity of the elements is based on +the electronic configuration or the num ber of protons in the nucleus. + + + 5 + + + +Salient features of the Modern Periodic Table: +The table has 18 vertical columns that are known by the name of groups and 7 +horizontal rows that are named as periods . +1) Periods: +● There are 7 periods in this table. The periods have the same +elements that have the same valence shell or the energy shell. +Example - Na, Mg, Al, Si, P, S, Cl are placed in the same shell as +they have the electronic shells as K, L and M. +● In a period, the number of electrons present in the energy shells +increase by 1 on moving from left to right within a period. Example +- Na - 1, Mg - 2, Al - 3, and so on. +● The number of elements present in a period can be determined by +the formula +22n , where n is the number of the shell from the +nucleus. Example: + + + + 6 +● The first period consists of two elements only namely, hydrogen +and helium as they have only 1 valence shell. Example - hydrogen +(Z = 1 or shell as K = 1), helium (Z = 2 or shell as K = 2) +● The second period has 8 elements with 2 shells and it starts with +lithium (Z = 3 o r shells as K = 2, L = 1) and ends with neon (Z = 10 +or shells as K = 2, L = 8).Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +● The first period consists of two elements only namely, hydrogen +and helium as they have only 1 valence shell. Example - hydrogen +(Z = 1 or shell as K = 1), helium (Z = 2 or shell as K = 2) +● The second period has 8 elements with 2 shells and it starts with +lithium (Z = 3 o r shells as K = 2, L = 1) and ends with neon (Z = 10 +or shells as K = 2, L = 8). +● The third period has 8 elements with 3 shells and it starts with +sodium (Z = 11 or shells as K = 2, L = 8, M = 1) and ends with +argon (Z = 18 or shells as K = 2, L = 8, M = 8 ). +● Similarly the fourth period has 18 elements with 4 shells and starts +with potassium (Z = 19) and ending with krypton (Z = 36). +● The fifth period having 18 elements with 5 shell starts with +rubidium (Z = 37) and ends with xenon (Z = 54). +● The sixth period with 32 elements has 6 shells and it starts with +caesium (Z = 55) ending with radon (Z = 86). +● The seventh and last period is incomplete with 19 elements starts +francium (Z = 87) and goes on till oganesson (Z = 118). +2) Groups: +● There are 18 grou ps in the periodic table. The group consists of +elements that have the same number of electrons in the valence shell +or outermost shell of the atom. +● The valence shell predominantly decides the physical or chemical +properties of the elements, so the elemen ts of the same group have +the same properties due to the same number of valence electrons. +Example - fluorine and chlorine have valence electrons as 7 and +they belong to group 17. + + 7 + +● The number of shells increases by one unit as the elements move +down in the periodic table in a group. +3) Blocks: +● The periodic table is also divided into 4 blocks that is based on the +subshell of the valence electrons. They are: +● s-Block elements : All the elements of group 1 and 2 are included +in this block and their general electronic configuration is +12nsPeriodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +● The number of shells increases by one unit as the elements move +down in the periodic table in a group. +3) Blocks: +● The periodic table is also divided into 4 blocks that is based on the +subshell of the valence electrons. They are: +● s-Block elements : All the elements of group 1 and 2 are included +in this block and their general electronic configuration is +12ns +Example - Hydrogen (H), Sodium (Na), etc from group 1 and +Magnesium (Mg), Calcium (Ca), etc from group 2. +● p-Block elem ents: This includes the elements from group 13 to 18. +They have an electronic configuration as +2 1 6ns np . +● d-block elements : This includes group 3 to 12 elements. They have +a general electronic configuration as +1 10 1 2n 1 d ns . +● f-block elements : This block has sets of elements, lanthanides and +the actinides. They have the electronic configuration of +1 14 0 1 2n 2 f n 1 d ns +. The lanthanides starts from Lanthanum +(La) - Lutetium (Lu) and the actinides starts from Actinium (Ac) - +Lawrencium (Lr). + +Position of elements in the periodic table: +● The position of the various elements are decided on the basis of their +valence shells and the number of electrons present in their valence +shells. Example - Sodium (Z - 11, 2,8,1), so it has 3 shells, so it is placed + + + 8 +in period 3 and since it has 1 valence electron in outermost shell, it is +placed in group 1. +● The position of an element in the periodic table determines its chemical +nature . Based on the position of the elements in the periodic table, they +can be classified as follows: +1) Noble gases: These are a group of elements placed in group 18, +which are tasteless, odourless monoatomic gases that have very low +chemical reactivity. There are 6 such gases, namely, Helium (He), +Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn). +They are also referred to as inert gases and due to their inertness ,Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +can be classified as follows: +1) Noble gases: These are a group of elements placed in group 18, +which are tasteless, odourless monoatomic gases that have very low +chemical reactivity. There are 6 such gases, namely, Helium (He), +Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn). +They are also referred to as inert gases and due to their inertness , +they are suitable to be used where reactions are not required. +Examp le - He is used by deep -sea divers in the breathing gas to +prevent toxicity of oxygen, nitrogen and carbon dioxide. +2) Normal elements: All the elements that are placed in groups 1 to 7 +are included in this. +3) Alkali metals: The elements in group 1, namely Lith ium (Li) - +Francium (Fr), except Hydrogen (H) are termed as alkali metals as +they tend to form hydroxide with water which are strong alkalis. +Thus alkali metals are very reactive and react quickly with water or +air. Example - Sodium (Na) reacts violently w ith oxygen in the air, +so it stored in mineral oil. +4) Alkaline earth metals: These include the group 2 elements starting +from Beryllium (Be) - Radium (Ra). They are less reactive than the +alkali metals that are found as a compound . +5) Transition elements: These include the elements from group 3 to +11. These are so named as they exhibit a transition in their +properties from the left to the right, including increase in atomic +size, ionization energy, electronegativity. +6) Inner transition elements: These are elements with similar +properties, placed at the end of group 3 in period 7 and 8. These are +called as the lanthanide series starting from Lanthanum (La) - +Lutetium (Lu) in period 6 with 14 elements. The period 7 contains +14 elements starting from Actinium (Ac) - Lawrencium (Lr). +7) Halogens: These include a group of elements in group 17 that are +generally non -metals that can exist in solid, liquid and gas form. + + 9Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +called as the lanthanide series starting from Lanthanum (La) - +Lutetium (Lu) in period 6 with 14 elements. The period 7 contains +14 elements starting from Actinium (Ac) - Lawrencium (Lr). +7) Halogens: These include a group of elements in group 17 that are +generally non -metals that can exist in solid, liquid and gas form. + + 9 +They react with the metals to form salts. They are Fluorine (F), +Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At) and +Tennessine (Ts). + +Properties of the periodic table: +1) Valency: +● The term valency denotes the number of electrons that are gained +or lost by an atom in order to complete its outermost shell to have a +stable electronic configuration. This valency is the number of +electrons present in the valence shell. +● It can be noted t hat the valency increases from left to right in a +period, and then decreases. +● The valency in the group remains the same through the group, +going downward. +● Example - Period 2 elements have atomic number from 3 to 10, so +they have 2 shells with increasing number of valence till C and then +it decreases. But all the group 2 elements have 2 electrons in their +outermost shell, so their valency is 2. + +2) Atomic size: +● The atomic size is determined by the atomic radius of the atom and +it can be termed as the distance from the centre of the nucleus of the +atom to its outermost shell. + + + 10 +● It is seen that the elements are placed across a period from left to +right, the atomic radius decreases . This is because an increased +nuclear charge has the tendency to pull the electrons towards the +nucleus, thereby decreasing the radius of the atom, and thus the +atomic size too decreases. +● It is not the same in a group. As the elements move down a group, +there is an addition of an extra shell, hence their atomic radius and +thus atomic size increases . Example -Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +nuclear charge has the tendency to pull the electrons towards the +nucleus, thereby decreasing the radius of the atom, and thus the +atomic size too decreases. +● It is not the same in a group. As the elements move down a group, +there is an addition of an extra shell, hence their atomic radius and +thus atomic size increases . Example - + +3) Ionization energy: +● It is termed as the amount of energy that is required to remove the +electrons that are present in the outermost shell of the atom. +● Across the period, since the atomic radius decreases, these electrons +in the outermost shell are much closer to the nucleus and therefore +it requires more energy to remove them. So, ionisation energy +increases across a period. +● In the groups, since a shell is being added down the group, so the +atomic radius increases which leads to the electrons in the +outermost shell being far from the nucleus and therefore it is easy +to remove them. Hence in a group, the ionisation energy decreases +going from top to bottom. + + + + 11 +4) Electron affinity: +● It is termed as the amount of energy change as a result of an addition +of an electron to the atom or the ability of an electron to accept +electrons. +● In a period, from left to right as the nuclear charge increases and +atomic size decreases, it is easy for the addition of electrons, which +leads to generation of more energy. Hence electron affinity +increases across a period. +● In the group, as atomic size increases, nuclear charge decreases, so +lesser number of electrons can be added which leads to lesser +energy generation. Hence electron affinity decreases from top to +bottom in a group . + +5) Metallic and non -metallic properties: +● The metals are those elements that have a tendency to lose electrons +and attain a positive charge. So, the metallic nature of elements +means that they are electropositive and have low ionization energy.Periodic Classification of Elements CBSE class 10 Notes Science Chapter 5 [PDF].txt +energy generation. Hence electron affinity decreases from top to +bottom in a group . + +5) Metallic and non -metallic properties: +● The metals are those elements that have a tendency to lose electrons +and attain a positive charge. So, the metallic nature of elements +means that they are electropositive and have low ionization energy. +This metallic character decreases along a period. +● Non-metallic nature of elements indicate that they have an ability +to gain electrons and attain a negative charge. So, this non -metallic +nature indicates that they are electronegative and have high +ionization energies. +● Hence this non-metallic nature increas es along a period . Hence, +moving along a period from left to right, the metallic character +decreases and non -metallic character increases and there is a semi - +metallic nature in between them. + + + 12 +● The metallic nature increases down a group as the atomic size +increases and they have an increased tendency of losing electrons. +Example - + +6) These trends can be summarised with the chart for easy reference:Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +CLASS - X SCIENCE +Chapter 6 - Life Processes + +What are life processes? +Biology is the study of living things . All living things are called organisms, both plants and +animals are living organisms. But how we decide whether something is living or non -living +depends on 7 life processes . If something is living it will carry out the 7 life processes below. + +1. Movement +Both animals and plants have the ability to move. Plants are rooted and move slowly as they +grow. Their roots move down into the soil and their stems move up towards the light. Animals +on the other hand move quickly and can move their entire bodies. They can move in search of +food, shelter or to avoid danger. + +2. Respiration +Respiration is the process of extracting energy out of the food we eat. All living things respire +because the y need energy to grow, to replace worn out parts and to move. Respiration takes +place in the mitochondria of the cell. + +3. Sensitivity +All living organisms are sensitive; this means that they have an awareness of changes in their +environment. Animals respond quickly to stimuli such as heat, light, sound, touch and +chemicals which have taste and smell. On the other hand, plants generally appear less sensitive +and their response is slower. + +4. Growth +All living organisms grow. Plants continue growing throughout t heir lives. Animals stop +growing once they reach adulthood. Even when growth stops, materials within an animal’s +body are still being replaced from its food. + +5. Excretion +All living things make waste products these can be useless or harmful to it and therefore need +to be got rid of. Excretion is the process of getting rid of metabolic waste. Plants store waste +substances in their leaves, the waste is removed when their leav es fall off. Animals breathe +out waste carbon dioxide, other waste substances leave the body in urine and sweat.Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +5. Excretion +All living things make waste products these can be useless or harmful to it and therefore need +to be got rid of. Excretion is the process of getting rid of metabolic waste. Plants store waste +substances in their leaves, the waste is removed when their leav es fall off. Animals breathe +out waste carbon dioxide, other waste substances leave the body in urine and sweat. +Note: Getting rid of faeces or undigested food is not excretion but egestion. + +6. Reproduction +All living things must produce offspring like themselves in order for their species to survive. +This is the process known as reproduction. Plants produce seeds that give rise to new plants +of the same species. Animals lay eggs or have babies. Reproduction can be of two types, +CLASS - X SCIENCE +Sexual which involves two parents and the union of two gametes and Asexual where one +parent can reproduce itself. + +7. Nutrition +Nutrition is needed for energy and growth, both plants and animals need food. Plants are able +to make their own food by photosynthesis. They use sunlight to turn simple molecules like +carbon dioxide and water into more complex carbohydrate molecules. Animals are unable to +make their own food so rely on other plants and other animals for their nutrition. Animals take +in complex substances and break them down i nto small, simple, soluble molecules which can +be used for energy and growth + +Nutrition: +Energy required to carry out different life processes is obtained through the process of nutrition. +Depending on the mode of obtaining nutrition, organisms are classif ied as autotrophs or +heterotrophs. +i. Autotrophs can prepare their own food from simple inorganic sources such as carbon dioxide +and water. Examples: Green plants and some bacteria. +ii. Heterotrophs cannot synthesise their own food and are dependent on oth er organisms for +obtaining complex organic substances for nutrition. Example: Animals and fungiLife Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +heterotrophs. +i. Autotrophs can prepare their own food from simple inorganic sources such as carbon dioxide +and water. Examples: Green plants and some bacteria. +ii. Heterotrophs cannot synthesise their own food and are dependent on oth er organisms for +obtaining complex organic substances for nutrition. Example: Animals and fungi + +Autotrophic Nutrition: +A type of nutrition in which organisms synthesize the organic materials they require from +inorganic sources. Chief sources of carbon and nitrogen are carbon dioxide and nitrates, +respectively. All green plants are autotrophic and use light as a source of energy for the synthesis +of food through photosynthesis. +2 2 6 12 6 2 2 +Glucose6 12 6 6Sunlight +ChlorophyllCO H O C H O H O O     + +The following events occur during this process. +(i) Absorption of light energy by chlorophyll +(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen +and oxygen. +(iii) Reduction of carbon dioxide to carbohydrates. + +These green plants absorbs water from the soil by roots. Co 2 enters from the atmosphere thr ough +stomata, Sunlight is absorbed by chlorophyll and other green parts of the plants. +Heterotrophic Nutrition: + +All heterotrophs depend on autotrophs for their nutrition. +The three main types of heterotrophic nutrition are: +1. Holozoic nutrition : Complex food is taken into a specialist digestive system and broken down +into small pieces to be absorbed. Eg: Ameoba, Humans +CLASS - X SCIENCE +2. Saprophytic nutrition : Organisms feed on dead organic remains of other organisms. Eg: Fungi +like bread moulds yeast and mushroom s. +3. Parasitic nutrition : Organisms obtain food from other living organisms (the host), with the +host receiving no benefit from the parasite. Eg: cascuta, ticks, lice, leeches and tape worms. + +How do Organisms Obtain Their Utrition?Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +2. Saprophytic nutrition : Organisms feed on dead organic remains of other organisms. Eg: Fungi +like bread moulds yeast and mushroom s. +3. Parasitic nutrition : Organisms obtain food from other living organisms (the host), with the +host receiving no benefit from the parasite. Eg: cascuta, ticks, lice, leeches and tape worms. + +How do Organisms Obtain Their Utrition? + + + +In single celled organisms, the food may be taken in by the entire surface. +Eg: Amoeba takes in food using temporary finger -like extensions of the cell surface which fuse +over the food particle forming a food -vacuole. Inside the food vacuole, complex subs tances are +broken down into simpler ones which then diffuse into the cytoplasm. The remaining undigested +material is moved to the surface of the cell and thrown out. + +Nutrition in Human Beings: +In humans, digestion of food takes place in the alimentary can al, made up of various organs and +glands. + +In the mouth, food is crushed into small particles through chewing and mixed with saliva, which +contains amylase for digesting starch. + +On swallowing, food passes through the pharynx and oesophagus to reach the st omach. Gastric +juice contains pepsin (for digesting proteins), HCl and mucus. + + +CLASS - X SCIENCE +The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin. +The mucus protects the inner lining of the stomach from the action of the acid under normal +conditions. + +From the stomach, the food now enters the small intestine. The small intestine is the site of the +complete digestion of carbohydrates, proteins and fats. +The liver secretes bile which emulsifies fat. +The pancreas secretes pancreat ic juice which contains the enzymes amylase, trypsin and lipase for +digesting starch, proteins and fats, respectively. + +In the small intestine, carbohydrates, proteins and fats are completely digested into glucose, +aminoacids, fatty acids and glycerol.Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +complete digestion of carbohydrates, proteins and fats. +The liver secretes bile which emulsifies fat. +The pancreas secretes pancreat ic juice which contains the enzymes amylase, trypsin and lipase for +digesting starch, proteins and fats, respectively. + +In the small intestine, carbohydrates, proteins and fats are completely digested into glucose, +aminoacids, fatty acids and glycerol. + +The villi of the small intestine absorb the digested food and supply it to every cell of the body. + +The unabsorbed food is sent into the large intestine where more villi absorb water from this +material. The rest of the material is removed from the body via t he anus. + +Respiration: + +During respiration, the digested food materials are broken down to release energy in the form of +ATP. +Depending on the requirement of oxygen, respiration may be of two types: +i. Aerobic respiration: It occurs in the presence of air (oxygen). +ii. Anaerobic respiration: It occurs in the absence of (air) oxygen. + +In all cases the first step is the break -down of glucose, a six -carbon molecule, into a three -caron +molecule called pyruvate . This process taken place in the cytoplasm. Further, the pyruvate may be +converted into ethanol and carbon dioxide. This process takes place in yeast during fermentation. +Since this process takes place in the absence of air (oxygen), it is called anaerobi c respiration. +Break -down of pyruvate using oxygen takes place in the mitochondria. +A large amount of energy is released in aerobic respiration as compared to anaerobic +respiration. +Some times when there is a lack of oxygen in our muscle cells, the pyruva te is converted into lactic +acid. This build up of lactic acid in our muscles during sudden activity causes cramps. +CLASS - X SCIENCE + + +Terrestrial organisms use atmospheric oxygen for respiration, whereas aquatic organisms use +oxygen dissolved in water.Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +respiration. +Some times when there is a lack of oxygen in our muscle cells, the pyruva te is converted into lactic +acid. This build up of lactic acid in our muscles during sudden activity causes cramps. +CLASS - X SCIENCE + + +Terrestrial organisms use atmospheric oxygen for respiration, whereas aquatic organisms use +oxygen dissolved in water. +In humans, inhalati on of air occurs through the following pathway: +Nostrils _ Nasal passage _ Pharynx _ Larynx _ Trachea _ Bronchus _ Bronchiole _ Alveolus +(please put arrow marks ------) + +In human beings are is taken into the body through the nostrils. The air passing thr ough the nostrils +is filtered by fine hairs that line the passage. The passage is also lined with mucus which helps in +this process. From here, the air passes through the throat and into the lungs. Rings of cartilage are +present in the throat. These ensure that the air -passage does not collapse. +Within the lungs the passage divides into smaller and smaller tubes which finally terminate in +balloon -line structures which are called alveoli. +The alveoli of lungs are richly supplied with blood and are the sit es where exchange of gases (O 2 +and CO 2) occurs between blood and the atmosphere. +The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the +oxygen in the alveolar air is taken up by blood in the alveolar blood vessels t o be transported to all + +CLASS - X SCIENCE +the cells in the body. During the breathing cycle, when air is taken in and let out, the lungs always +contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for +the carbon dioxide to be relea sed. +In humans, the respiratory pigment haemoglobin carries oxygen from the lungs to the different +tissues of the body. This pigment in present in the red blood cells. + +Transportation : +Transportation in Human Beings :Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for +the carbon dioxide to be relea sed. +In humans, the respiratory pigment haemoglobin carries oxygen from the lungs to the different +tissues of the body. This pigment in present in the red blood cells. + +Transportation : +Transportation in Human Beings : +The circulatory system is composed of the heart, blood and blood vessels which transport various +materials throughout the body. + +The heart: + + + + +CLASS - X SCIENCE +The human heart has four chambers —two atria (right and left) and two ventricles (right and left). +These chambers prevent the oxygen rich blood from m ixing with the blood containing carbon +dioxide. The right half of the heart receives deoxygenated blood, whereas the left half receives +oxygenated blood. +The carbon dioxide –rich blood has to reach the lungs for the carbon dioxide to be removed, and +the ox ygenated blood from the lungs has to be brought back to the heart. This oxygen -rich blood +is then pumped to the rest of the body. +Ventricular walls are much thicker than atrial walls. +Humans show double circulation i.e. blood goes through the heart twice a nd complete separation +of oxygenated and deoxygenated blood. +Arteries carry blood from the heart to different parts of the body, whereas veins deliver the blood +back to the heart. Arteries are connected to veins by thin capillaries, wherein materials are +exchanged between the blood and cells. +Blood has platelet cells which circulates around the body and prevent the blood loss at the site of +injury. +Lymph is also involved in transportation. It is similar to the plasma of blood but colourless and +contains les s protein. It drains into lymphatic capillaries from the intercellular spaces which join +to from large lymph vessels that finally open into larger veins. It carries digested and absorbed fatLife Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +injury. +Lymph is also involved in transportation. It is similar to the plasma of blood but colourless and +contains les s protein. It drains into lymphatic capillaries from the intercellular spaces which join +to from large lymph vessels that finally open into larger veins. It carries digested and absorbed fat +from intestine and drains excess fluid from extra cellular space back into the blood. + +Transportation in plants : +Plant transport systems will move energy stores from leaves and raw materials from roots. These +two pathways are constructed as independently organized conducting tubes. One, the xylem moves +water and minerals obtained from the soil. The other, phloem tran sports products of photosynthesis +from the leaves where they are synthesised to other parts of the plant. + +The component of xylem tissue ( tracheids and vessesls) of roots, stems, leaves are interconnected +to form a continuous system of water conducting ch annels that reaches all parts of the plant. +Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells +of the roots. Then there is a steady movement of water from the root xylem to all parts of the plant +parts thro ugh the interconnected water conducting channels. + +The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration . +Thus it helps in the absorption and upward movement of water and minerals dissolved in it from +roots t o the leaves. It also regulates temperature. +The transport of soluble products of photosynthesis is called translocation and it occurs in phloem. +It transports amino acids and other substances. The translocation of food and other substances +takes place in the sieve tubes with the help of adjacent companion cells both in upward and down +ward directions. + +CLASS - X SCIENCE +The translocation in phloem is achieved by utilising energy. Material like sucrose is transferredLife Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +It transports amino acids and other substances. The translocation of food and other substances +takes place in the sieve tubes with the help of adjacent companion cells both in upward and down +ward directions. + +CLASS - X SCIENCE +The translocation in phloem is achieved by utilising energy. Material like sucrose is transferred +into phloem tissue using energy from ATP. This increases t he osmotic pressure of the tissue +causing water to move into it. This pressure. This allows the phloem to move material according +to the plant’s needs. For example, in the spring, sugar stored in root or stem tissue would be +transported to the buds which n eed energy to grow. + +Excretion: +During excretion, the harmful metabolic nitrogenous wastes generated are removed from the body + +Excretion in Human Beings: +In humans, a pair of kidneys, a pair of ureters, the urinary bladder and the urethra constitute the +excretory system. Kidneys are located in the addomen, one on either side of the backbone. Urine +produced in the kidneys passes through the ureters into the urinary bladder where it is stored until +it is released through the urethra. + +Each kidney has large numbers of basic filtration units called nephrons. Some substances in the +initial filtrate, such as glucose, amino acids, salts and a major amount of water , are selectively re - +absorbed as the urine flows along the tube. The amount of water re -absorbed depends on how +much excess water there is in the body, and on how much of dissolved waste there is to be excreted. +The urine forming in each kidney eventually enters a long tube, the ureter, which connects the +kidneys with the urinary bladder until the pressure of the expanded bladder leads to the urge to +pass it out through the urethra. The bladder is muscular so it is under nervous control. As a result +we can control the urge to urinate. + +Excretion in plants :Life Processes CBSE class 10 Notes CBSE Science Chapter 6 [PDF].txt +The urine forming in each kidney eventually enters a long tube, the ureter, which connects the +kidneys with the urinary bladder until the pressure of the expanded bladder leads to the urge to +pass it out through the urethra. The bladder is muscular so it is under nervous control. As a result +we can control the urge to urinate. + +Excretion in plants : +Plants do not have an excretory system and carry out excretion in various ways such as +transpiration, releasing wastes into the surrounding soil, losing their leaves and storing waste +materials in cell vacuoles. Other waste products are stored as resins and gums in old xylem.cbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +Corrosion +Alloys +Alloys are homogeneous mixtures of metal with other metals or nonmetals. Alloy formation +enhances the desirable properties of the material, such as hardness, tensile strength and +resistance to corrosion. +Examples of few alloys - +Brass: copper and zinc +Bronze: copper and tin +Solder: lead and tin +Amalgam: mercury and other metal +Corrosion +Gradual deterioration of a material usually a metal by the action of moisture, air or +chemicals in the surrounding environment. +Rusting: +4Fe(s) + 3O 2(from  air) + xH 2O(moisture ) → 2Fe 2O3.xH 2O(rust) +Corrosion of copper: +Cu(s) +H2O(moisture ) +CO 2(from  air) → CuCO 3.Cu(OH)2(green ) +Corrosion of silver: +Ag(s) +H2S(from  air) → Ag2S(black) + H2(g) +Prevention of CorrosionPrevention :  +1. Coating with paints or oil or grease: Application of paint or oil or grease on metal surfaces +keep out air and moisture. +2. Alloying: Alloyed metal is more resistant to corrosion. Example: stainless steel. +3. Galvanization: This is a process of coating molten zinc on iron articles. Zinc forms a +protective layer and prevents corrosion. +4. Electroplating: It is a method of coating one metal with another by use of electric current. +This method not only lends protection but also enhances the metallic appearance. +Example: silver plating, nickel plating. +5. Sacrificial protection: Magnesium is more reactive than iron. When it is coated on the +articles made of iron or steel, it acts as the cathode, undergoes reaction (sacrifice) instead +of iron and protects the articles.Metals and Non-metalsPhysical Properties +Physical Properties of Metals +●Hard and have a high tensile strength +●Solids at room temperature +●Sonorous +●Good conductors of heat and electricity +●Malleable, i.e., can be beaten into thin sheets +●Ductile, i.e., can be drawn into thin wires +●High melting and boiling points (except Caesium (Cs) and Gallium (Ga)) +●Dense, (except alkali metals). Osmium - highest density and lithium - least density +●Lustrouscbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +●Hard and have a high tensile strength +●Solids at room temperature +●Sonorous +●Good conductors of heat and electricity +●Malleable, i.e., can be beaten into thin sheets +●Ductile, i.e., can be drawn into thin wires +●High melting and boiling points (except Caesium (Cs) and Gallium (Ga)) +●Dense, (except alkali metals). Osmium - highest density and lithium - least density +●Lustrous +●Silver-grey in colour, (except gold and copper) +Non-Metals +Nonmetals are those elements which do not exhibit the properties of metals. +Physical Properties of Nonmetals +Occur as solids, liquids and gases at room temperature +Brittle +Non-malleable +Non-ductile +Non-sonorous +Bad conductors of heat and electricity +Exceptions in Physical Properties +Alkali metals (Na, K, Li) can be cut using a knife. +Mercury is a liquid metal. +Lead and mercury are poor conductors of heat. +Mercury expands significantly for the slightest change in temperature. +Gallium and caesium have a very low melting point +Iodine is non-metal but it has lustre. +Graphite conducts electricity. +Diamond conducts heat and has a very high melting point. +Chemical Properties +Chemical Properties of Metals●Alkali metals (Li, Na, K, etc) react vigorously with water and oxygen or air. +●Mg reacts with hot water. +●Al, Fe and Zn react with steam. +●Cu, Ag, Pt, Au do not react with water or dilute acids. +Reaction of Metals with Oxygen (Burnt in Air) +Metal + Oxygen  →  Metal oxide (basic) +●Na and K are kept immersed in kerosene oil as they react vigorously with air and catch +fire. + 4K(s) +O2(g) → 2K 2O(s) (vigorous reaction) +●Mg, Al, Zn, Pb react slowly with air and form a protective layer that prevents corrosion. +2Mg (s) +O2(g) → 2MgO (s) (Mg burns with a white dazzling light) +4Al(s) + 3O 2(g) → 2Al 2O3(s) +●Silver, platinum and gold don't burn or react with air. +Basic Oxides of Metals +Some metallic oxides get dissolved in water and form alkalis. Their aqueous solution turns +red litmus blue. +Na 2O(s) +H2O(l) → 2NaOH (aq) +K2O(s) +H2O(l) → 2KOH (aq)cbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +2Mg (s) +O2(g) → 2MgO (s) (Mg burns with a white dazzling light) +4Al(s) + 3O 2(g) → 2Al 2O3(s) +●Silver, platinum and gold don't burn or react with air. +Basic Oxides of Metals +Some metallic oxides get dissolved in water and form alkalis. Their aqueous solution turns +red litmus blue. +Na 2O(s) +H2O(l) → 2NaOH (aq) +K2O(s) +H2O(l) → 2KOH (aq) +Amphoteric Oxides of Metals +Amphoteric oxides are metal oxides which react with both acids as well as bases to form +salt and water. +For example - Al 2O3,ZnO ,PbO ,SnO +Al2O3(s) + 6HCl (aq) → 2AlCl 3(aq) + 3H 2O(l) +Al2O3(s) + 2NaOH (aq) → 2NaAlO 2(aq) +H2O(l) +ZnO (s) + 2HCl (aq) →ZnCl 2(aq) +H2O(l) +ZnO (s) + 2NaOH (aq) →Na 2ZnO 2(aq) +H2O(l) +Reactivity Series +The below table illustrates the reactivity of metals from high order to low order. +Symbol               ElementK Potassium ( Highly Active Metal) +Ba Barium +Ca Calcium +Na Sodium +Mg Magnesium +Al Aluminium +Zn Zinc +Fe Iron +Ni Nickel +Sn Tin +Pb Lead +H Hydrogen +Cu Copper +Hg Mercury +Ag Silver +Au Gold +Pt Platinum +Reaction of Metals with Water or Steam +Metal +Water →Metal  hydroxide  or Metal  oxide +Hydrogen +2Na + 2H 2O(cold) → 2NaOH +H2+heat +Ca+ 2H 2O(cold) →Ca(OH)2+H2 +Mg+ 2H 2O(hot) →Mg(OH)2+H2 +2Al+ 3H 2O(steam ) →Al2O3+ 3H 2 +Zn+H2O(steam ) →ZnO +H2 +3Fe + 4H 2O(steam ) →Fe3O4+ 4H 2 +Reaction of Metals with Acid +Metal +dilute  acid →Salt +Hydrogen  gas +2Na(s) + 2HCl (dilute ) → 2NaCl (aq) +H2(g) +2K(s) +H2SO 4(dilute ) →K2SO 4(aq) +H2(g) +Only Mg and Mn, react with very dilute nitric acid to liberate hydrogen gas.  +Mg(s) + 2HNO 3(dilute ) →Mg(NO 3)2(aq) +H2(g) +Mn(s) + 2HNO 3(dilute ) →Mn(NO 3)2(aq) +H2(g) +Displacement ReactionA more reactive element displaces a less reactive element from its compound or solution. +How Do Metal React with Solution of Other Metal Salts +Metal  A+Salt of  metal  B→Salt of  metal  A+Metal  B +Fe(s) +CuSO 4(aq) →FeSO 4(aq) +Cu(s) +Cu(s) + 2AgNO 3(aq) →Cu(NO 3)(aq) + 2Ag (s) +Reaction of Metals with Bases +Base +metal →salt+hydrogencbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +Displacement ReactionA more reactive element displaces a less reactive element from its compound or solution. +How Do Metal React with Solution of Other Metal Salts +Metal  A+Salt of  metal  B→Salt of  metal  A+Metal  B +Fe(s) +CuSO 4(aq) →FeSO 4(aq) +Cu(s) +Cu(s) + 2AgNO 3(aq) →Cu(NO 3)(aq) + 2Ag (s) +Reaction of Metals with Bases +Base +metal →salt+hydrogen +2NaOH (aq) +Zn(s) →Na 2ZnO 2(aq) +H2(g) +2NaOH (aq) + 2Al (s) + 2H 2O(l) → 2NaAlO 2(aq) + 2H 2(g) +Extraction of Metals and Non-Metals +Applications of Displacement Reaction +Uses of displacement reaction +1. Extraction of metals +2. Manufacturing of steel +3. Thermite reaction: Al( s) +Fe2O3(s) →Al2O3+Fe(molten ) +The thermite reaction is used in welding of railway tracks, cracked machine parts, etc. +Occurrence of Metals +Most of the elements especially metals occur in nature in the combined state with other +elements. All these compounds of metals are known as  minerals. But out of them, only a few +are viable sources of that metal. Such sources are called ores. +Au, Pt - exist in the native or free state. +Extraction of MetalsMetals of high reactivity - Na, K, Mg, Al. +Metals of medium reactivity - Fe, Zn, Pb, Sn. +Metals of low reactivity - Cu, Ag, Hg +Roasting +Converts sulphide ores into oxides on heating strongly in the presence of excess air. +It also removes volatile impurities. +2ZnS (s) + 3O 2(g) +Heat → 2ZnO (s) + 2SO 2(g) +Calcination +Converts carbonate and hydrated ores into oxides on heating strongly in the presence of +limited air. It also removes volatile impurities. +ZnCO 3(s) +heat →ZnO (s) +CO 2(g) +CaCO 3(s) +heat →CaO (s) +CO 2(g) +Al2O3.2H 2O(s) +heat → 2Al 2O3(s) + 2H 2O(l) +2Fe 2O3.3H 2O(s) +heat → 2Fe 2O3(s) + 3H 2O(l) +Extracting Metals Low in Reactivity SeriesBy self-reduction- when the sulphide ores of less electropositive metals like Hg, Pb, Cu etc., +are heated in air, a part of the ore gets converted to oxide which then reacts with thecbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +ZnCO 3(s) +heat →ZnO (s) +CO 2(g) +CaCO 3(s) +heat →CaO (s) +CO 2(g) +Al2O3.2H 2O(s) +heat → 2Al 2O3(s) + 2H 2O(l) +2Fe 2O3.3H 2O(s) +heat → 2Fe 2O3(s) + 3H 2O(l) +Extracting Metals Low in Reactivity SeriesBy self-reduction- when the sulphide ores of less electropositive metals like Hg, Pb, Cu etc., +are heated in air, a part of the ore gets converted to oxide which then reacts with the +remaining sulphide ore to give the crude metal and sulphur dioxide. In this process, no +external reducing agent is used. +1.2HgS (Cinnabar) + 3O 2(g) +heat → 2HgO (crude  metal ) + 2SO 2(g) +2HgO (s) +heat → 2Hg (l) +O2(g) +2.Cu2S(Copper pyrite ) + 3O 2(g) +heat → 2Cu 2O(s) + 2SO 2(g) +2Cu 2O(s) +Cu2S(s) +heat → 6Cu(crude  metal ) +SO 2(g) +3.2PbS (Galena) + 3O 2(g) +heat → 2PbO (s) + 2SO 2(g) +PbS(s) + 2PbO (s) → 2Pb (crude  metal ) +SO 2(g) +Extracting Metals in the Middle of Reactivity Series +Smelting - it involves heating the roasted or calcined ore(metal oxide) to a high temperature +with a suitable reducing agent. The crude metal is obtained in its molten state. +Fe2O3+ 3C (coke) → 2Fe + 3CO 2 +Aluminothermic reaction - also known as the Goldschmidt reaction is a highly exothermic +reaction in which metal oxides usually of Fe and Cr are heated to a high temperature with +aluminium. +Fe2O3+ 2Al →Al2O3+ 2Fe +heat +Cr2O3+ 2Al →Al2O3+ 2Cr +heat +Extraction of Metals Towards the Top of the Reactivity Series +Electrolytic reduction: +1. Down’s process:  Molten NaCl is electrolysed in a special apparatus. +At the cathode (reduction) -  +Na+(molten ) +e−→Na(s) +Metal is deposited. +At the anode (oxidation) - +2Cl−(molten ) →Cl2(g) + 2e– +Chlorine gas is liberated. +2. Hall’s process: Mixture of molten alumina and a fluoride solvent usually cryolite, +(Na 3AlF 6) is electrolysed. +At the cathode (reduction) - +2Al3++ 6e–→ 2Al (s)Metal is deposited. +At the anode (oxidation) - +6O2–→ 3O 2(g) + 12e–  +Oxygen gas is liberated. +Enrichment of Orescbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +Na+(molten ) +e−→Na(s) +Metal is deposited. +At the anode (oxidation) - +2Cl−(molten ) →Cl2(g) + 2e– +Chlorine gas is liberated. +2. Hall’s process: Mixture of molten alumina and a fluoride solvent usually cryolite, +(Na 3AlF 6) is electrolysed. +At the cathode (reduction) - +2Al3++ 6e–→ 2Al (s)Metal is deposited. +At the anode (oxidation) - +6O2–→ 3O 2(g) + 12e–  +Oxygen gas is liberated. +Enrichment of Ores +It means removal of impurities or gangue from ore, through various physical and chemical +processes. The technique used for a particular ore depends on the difference in the +properties of the ore and the gangue. +Refining of Metals +Refining of metals - removing impurities or gangue from crude metal. It is the last step in +metallurgy and is based on the difference between the properties of metal and the gangue. +Electrolytic Refining +Metals like copper, zinc, nickel, silver, tin, gold etc., are refined electrolytically. +Anode – impure or crude metal +Cathode – thin strip of pure metal +Electrolyte – aqueous solution of metal salt +From anode  (oxidation) - metal ions are released into the solution +At cathode (reduction) - equivalent amount of metal from solution is deposited +Impurities deposit at the bottom of the anode. +The Why Questions +Electronic configuration + Group 1 elements - Alkali metals +Element Electronic  configuration +Lithium (Li) 2, 1 +Sodium (Na) 2, 8, 1 +Potassium (K) 2, 8, 8, 1 +Rubidium (Rb) 2, 8, 18, 8, 1 Group 2 elements - Alkaline earth metals +Element Electronic  configuration +Beryllium (Be) 2, 2 +Magnesium (Mg ) 2, 8, 2 +Calcium (Ca) 2, 8, 8, 2 +Stronium (Sr) 2, 8, 18, 8, 2 +How Do Metals and Nonmetals React +Metals lose valence electron(s) and form cations. +Non-metals gain those electrons in their valence shell and form anions. +The cation and the anion are attracted to each other by strong electrostatic force, thus +forming an ionic bond.  +For example: In Calcium chloride, the ionic bond is formed by oppositely charged +calcium and chloride ions.cbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +How Do Metals and Nonmetals React +Metals lose valence electron(s) and form cations. +Non-metals gain those electrons in their valence shell and form anions. +The cation and the anion are attracted to each other by strong electrostatic force, thus +forming an ionic bond.  +For example: In Calcium chloride, the ionic bond is formed by oppositely charged +calcium and chloride ions. +Calcium atom loses 2 electrons and attains the electronic configuration of the nearest noble +gas (Ar). By doing so, it gains a net charge of +2. +The two Chlorine atoms take one electron each, thus gaining a charge of -1 (each) and attain +the electronic configuration of the nearest noble gas (Ar). +Ionic CompoundsThe electrostatic attractions between the oppositely charged ions hold the compound +together. +Example: MgCl 2,CaO ,MgO ,NaCl ,etc . +Properties of Ionic Compound +Ionic compounds +1. Are usually crystalline solids (made of ions). +2. Have high melting and boiling points. +3. Conduct electricity when in aqueous solution and when melted. +4. Are mostly soluble in water and polar solvents. +Physical Nature +Ionic solids usually exist in a regular, well-defined crystal structures. +Electric Conduction of Ionic Compounds +Ionic compounds conduct electricity in the molten or aqueous state when ions become free +and act as charge carriers. +In solid form, ions are strongly held by electrostatic forces of attractions and not free to +move; hence do not conduct electricity. +For example, ionic compounds such as NaCl does not conduct electricity when solidconduct electricity but when dissolved in water or in molten state, it will +conduct  electricity. +Salt solution conducts electricity +Melting and Boiling Points of Ionic Compounds +In ionic compounds, the strong electrostatic forces between ions require a high amount of +energy to break. Thus, the melting point and boiling point of an ionic compound are usually +very high. +Solubility of Ionic Compoundscbse-CBSE class-10-science-notes-chapter-3-metals-and-non-metals.txt +conduct  electricity. +Salt solution conducts electricity +Melting and Boiling Points of Ionic Compounds +In ionic compounds, the strong electrostatic forces between ions require a high amount of +energy to break. Thus, the melting point and boiling point of an ionic compound are usually +very high. +Solubility of Ionic Compounds +Most ionic compounds are soluble in water due to the separation of ions by water. This +occurs due to the polar nature of water. For example, NaCl is a 3-D salt crystal composed of Na+ and Cl− ions bound together +through electrostatic forces of attractions. When a crystal of NaCl comes into contact with +water, the partial positively charged ends of water molecules interact with the Cl− ions, +while the negatively charged end of the water molecules interacts with the Na+ ions. +This ion-dipole interaction between ions and water molecules assist in the breaking of the +strong electrostatic forces of attractions within the crystal and ultimately in the solubility of +the crystal.cbse-CBSE class-10-science-notes-chapter-2-acids-bases-and-salts.txt +Acids, Bases and Salts +Introduction to Acids, Bases and Salts +Classification of matter +On the basis of +a) composition -  elements, compounds and mixtures +b) state - solids, liquids and gases +c) solubility - suspensions, colloids and solutions +Types of mixtures - homogeneous and heterogeneous +Types of compounds - covalent and ionic +What Is an Acid and a Base? +Ionisable and non-ionisable compounds +An ionisable compound when dissolved in water or in its molten state, dissociates into ions +almost entirely. Example: NaCl, HCl, KOH, etc. +A non-ionisable compound does not dissociate into ions when dissolved in water or in its +molten state. Example: glucose, acetone, etc. +Arrhenius theory of acids and bases +Arrhenius acid - when dissolved in water, dissociates to give H+(aq) or H 3O+ ion. +Arrhenius base - when dissolved in water, dissociates to give OH− ion. +Examples Acids  +Hydrochloric acid (HCl ) +Sulphuric acid  (H 2SO 4) +Nitric acid (HNO 3) +Bases  +Sodium hydroxide (NaOH) +Potassium hydroxide (KOH) +Calcium hydroxide (Ca(OH)2) +Bronsted Lowry theoryA Bronsted acid is a H+(aq) ion donor. +A Bronsted base is a H+(aq) ion acceptor. +Example +In the reaction:  HCl(aq) +NH 3(aq) →NH+ +4(aq) +Cl−(aq) +HCl - Bronsted acid and Cl− - its conjugate acid +NH 3  - Bronsted base and NH+ +4 - its conjugate acid +Physical test +Given are two possible physical tests to identify an acid or a base. +a. Taste +An acid tastes sour whereas a base tastes bitter. +The method of taste is not advised as an acid or a base could be contaminated or corrosive. +b. Effect on indicators by acids and bases +An indicator is a chemical substance which shows a change in its physical properties, +mainly colour or odour when brought in contact with an acid or a base. +Below mentioned are commonly used indicators and the different colours they exhibit:  +a) Litmus +In neutral solution - purple +In acidic solution - red +In basic solution - bluecbse-CBSE class-10-science-notes-chapter-2-acids-bases-and-salts.txt +b. Effect on indicators by acids and bases +An indicator is a chemical substance which shows a change in its physical properties, +mainly colour or odour when brought in contact with an acid or a base. +Below mentioned are commonly used indicators and the different colours they exhibit:  +a) Litmus +In neutral solution - purple +In acidic solution - red +In basic solution - blue +Litmus is also available as strips of paper in two variants - red litmus and blue litmus. +An acid turns a moist blue litmus paper to red. +A base turns a moist red litmus paper to blue. +b) Methyl orange +In neutral solution - orange +In acidic solution - red +In basic solution - yellow +c) Phenolphthalein +In neutral solution - colourless +In acidic solution - remains colourless +In basic solution - pink +Acid Base ReactionsReactions of acids and bases +a) Reaction of acids and bases with metals +Acid + active metal →  salt + hydrogen + heat +2HCl   +Mg→MgCl 2+H2(↑) +Base + metal → salt + hydrogen + heat +2NaOH   +Zn→Na 2ZnO 2+H2(↑) +A more reactive metal displaces the less reactive metal from its base. +2Na +Mg(OH)2→ 2NaOH +Mg +b) Reaction of acids with metal carbonates and bicarbonates +Acid + metal carbonate or bicarbonate  →  salt + water + carbon dioxide. +2HCl   +  CaCO 3→CaCl 2  +  H 2O  +  CO 2 +H2SO 4  +  Mg (HCO 3)2→MgSO 4  +  2H 2O  +  2CO 2 +Effervescence indicates liberation of  CO 2 gas. +c) Neutralisation reaction +1. Reaction of metal oxides and hydroxides with acids +Metal oxides or metal hydroxides are basic in nature. +Acid + base → salt + water + heat +H2SO 4  +  MgO →MgSO 4  +  H 2O +2HCl +Mg(OH)2→MgCl 2+ 2H 2O +2. Reaction of non-metal oxides with bases +Non-metal oxides are acidic in nature +Base + Non-metal oxide  →  salt + water + heat +2NaOH +CO 2→Na 2CO 3+H2O +Water +Acids and bases in water +When added to water, acids and bases dissociate into their respective ions and help in +conducting electricity. +Difference between a base and an alkali +Base-Bases undergo neutralisation reaction with acids.cbse-CBSE class-10-science-notes-chapter-2-acids-bases-and-salts.txt +2. Reaction of non-metal oxides with bases +Non-metal oxides are acidic in nature +Base + Non-metal oxide  →  salt + water + heat +2NaOH +CO 2→Na 2CO 3+H2O +Water +Acids and bases in water +When added to water, acids and bases dissociate into their respective ions and help in +conducting electricity. +Difference between a base and an alkali +Base-Bases undergo neutralisation reaction with acids. +They are comprised of metal oxides, metal hydroxides, metal carbonates and metal +bicarbonates. +Most of them are insoluble in water.  +Alkali -  +An alkali is an aqueous solution of a base, (mainly metallic hydroxides). +It dissolves in water and dissociates to give   OH− ion. +All alkalis are bases, but not all bases are alkalis. +Hydronium ion +Hydronium ion is formed when a hydrogen ion accepts a lone pair of electrons from the +oxygen atom of a water molecule, forming a coordinate covalent bond. +Formation of a hydronium ion +Dilution +Dilution is the process of reducing the concentration of a solution by adding more solvent +(usually water) to it. +It is a highly exothermic process. +To dilute an acid, the acid must be added to water and not the other way round. +Strength of acids and basesStrong acid or base : When all molecules of given amount of an acid or a base dissociate +completely in water to furnish their respective ions, H+(aq)  for acid and OH−(aq) for base). +Weak acid or base: When only a few of the molecules of given amount of an acid or a base +dissociate in water to furnish their respective ions, H+(aq) for acid and OH−(aq) for base).  +Dilute acid: contains less number of H+(aq) ions per unit volume. +Concentrated acid: contains more number of H+(aq) ions per unit volume.Universal indicator +A universal indicator has pH range from 0 to 14 that indicates the acidity or alkalinity of a +solution. +A neutral solution has pH=7 +pH +       pH= −log 10[H+] +In pure water,  [H+] = [OH−] = 10−7 mol/L. Hence, the pH of pure water is 7. +The pH scale ranges from 0 to 14.cbse-CBSE class-10-science-notes-chapter-2-acids-bases-and-salts.txt +Concentrated acid: contains more number of H+(aq) ions per unit volume.Universal indicator +A universal indicator has pH range from 0 to 14 that indicates the acidity or alkalinity of a +solution. +A neutral solution has pH=7 +pH +       pH= −log 10[H+] +In pure water,  [H+] = [OH−] = 10−7 mol/L. Hence, the pH of pure water is 7. +The pH scale ranges from 0 to 14. +If pH < 7 - acidic solution +If pH > 7-  basic solution +pH scale +Importance of pH in everyday life1. pH sensitivity of plants and animals +Plants and animals are sensitive to pH. Crucial life processes such as digestion of food, +functions of enzymes and hormones happen at a certain pH value. +2. pH of a soil +The pH of a soil optimal for the growth of plants or crops is 6.5 to 7.0. +3. pH in the digestive system +The process of digestion happens at a specific pH in our stomach which is 1.5 - 4. +The pH of the interaction of enzymes, while food is being digested, is influenced by HCl in +our stomach.  +4. pH in tooth decay +Tooth decay happens when the teeth are exposed to an acidic environment of pH +5.5 and below.   +5. pH of self-defense by animals and plants +Acidic substances are used by animals and plants as a self-defense mechanism. For example, +bee and plants like nettle secrete a highly acidic substance for self-defense. These secreted +acidic substances have a specific pH. +Manufacture of Acids and Bases +Manufacture of acids and bases +a) Non-metal oxide + water → acid +SO2(g) +H2O(l) →H2SO3(aq) +SO3(g) +H2O(l) →H2SO4(aq) +4NO 2(g) + 2H 2O(l) +O2(g) → 4HNO 3(aq) +Non-metal oxides are thus referred to as acid anhydrides. +b) Hydrogen + halogen → acid +H2(g) +Cl2(g) → 2HCl (g) +HCl(g) +H2O(l) →HCl(aq) +c) Metallic salt + conc. sulphuric acid → salt + more volatile acid +2NaCl (aq) +H2SO4(aq) →Na2SO4(aq) + 2HCl (aq) +2KNO 3(aq) +H2SO4(aq) →K2SO4(aq) + 2HNO 3(aq)d) Metal + oxygen → metallic oxide (base) +4Na( s) +O2(g) → 2Na 2O(s) +2Mg (s) +O2(g) → 2MgO (s) +e) Metal + water → base or alkali + hydrogen +Zn(s) + H2O(steam ) → ZnO(s)+ H 2(g)cbse-CBSE class-10-science-notes-chapter-2-acids-bases-and-salts.txt +H2(g) +Cl2(g) → 2HCl (g) +HCl(g) +H2O(l) →HCl(aq) +c) Metallic salt + conc. sulphuric acid → salt + more volatile acid +2NaCl (aq) +H2SO4(aq) →Na2SO4(aq) + 2HCl (aq) +2KNO 3(aq) +H2SO4(aq) →K2SO4(aq) + 2HNO 3(aq)d) Metal + oxygen → metallic oxide (base) +4Na( s) +O2(g) → 2Na 2O(s) +2Mg (s) +O2(g) → 2MgO (s) +e) Metal + water → base or alkali + hydrogen +Zn(s) + H2O(steam ) → ZnO(s)+ H 2(g) +f) Few metallic oxides + water → alkali +Na 2O(s) +H2O(l) → 2NaOH (aq) +g) Ammonia + water → ammonium hydroxide +NH 3(g) +H2O(l) →NH 4OH(aq) +Salts +Salts +A salt is a combination of an anion of an acid and a cation of a base. +Examples - KCl ,NaNO 3,CaSO 4,etc. +Salts are usually prepared by neutralisation reaction of an acid and a base. +Common salt +Sodium Chloride (NaCl) is referred to as common salt because it’s used all over the world for +cooking. +Family of salts +Salts having the same cation or anion belong to the same family. For example, NaCl, KCl, +LiCl. +pH of salts +A salt of a strong acid and a strong base will be neutral in nature. pH = 7 (approx.). +A salt of a weak acid and a strong base will be basic in nature. pH > 7. +A salt of a strong acid and a weak base will be acidic in nature. pH < 7. +The pH of a salt of a weak acid and a weak base is determined by conducting a pH test. +Preparation of Sodium hydroxide  +Chemical formula - NaOH +Also known as - caustic sodaPreparation (Chlor-alkali process): +Electrolysis of brine (solution of common salt, NaCl) is carried out.At anode: Cl 2 is released +At cathode: H2 is released +Sodium hydroxide remains in the solution. +Bleaching powder +Chemical formula - Ca(OCl)Cl or CaOCl 2 +Preparation - Ca( OH)2(aq) +Cl2(g) →CaOCl 2(aq) +H2O(l) +On interaction with water - bleaching powder releases chlorine which is responsible for +bleaching action. +Baking soda +Chemical name - Sodium hydrogen carbonate +Chemical formula - NaHCO 3 +Preparation (Solvay process) -  +a. Limestone is heated:  CaCO 3→CaO +CO 2cbse-CBSE class-10-science-notes-chapter-2-acids-bases-and-salts.txt +Bleaching powder +Chemical formula - Ca(OCl)Cl or CaOCl 2 +Preparation - Ca( OH)2(aq) +Cl2(g) →CaOCl 2(aq) +H2O(l) +On interaction with water - bleaching powder releases chlorine which is responsible for +bleaching action. +Baking soda +Chemical name - Sodium hydrogen carbonate +Chemical formula - NaHCO 3 +Preparation (Solvay process) -  +a. Limestone is heated:  CaCO 3→CaO +CO 2 +b. CO_2 is passed through a concentrated solution of sodium chloride and ammonia : +NaCl (aq) +NH 3(g) +CO 2(g) +H2O(l) →NaHCO 3(aq) +NH 4Cl(aq) +Uses: +1. Textile industry +2. Paper industry +3. Disinfectant +Washing soda +Chemical name  - Sodium carbonate decahydrate. +Chemical formuala - \(Na_2CO_3 \) +Preparation: By heating NaHCO 3 +2NaHCO 3(s) →Na 2CO 3(s) +CO 2(g) +H2O(g) +Na 2CO 3(s)  +  10H 2O(l)  →  Na 2CO 3.10H 2O(s)Uses +1. In glass, soap and paper industries +2. Softening of water +3. Domestic cleaner +Crystals of salts +Certain salts form crystals by combining with a definite proportion of water. The water that +combines with the salt is called water of crystallisation. +Plaster of parisGypsum ,  CaSO 4.2H 2O (s) on  heating  at 100°C  (373K ) gives  CaSO 4.H2O and  H2O +CaSO 4.H2O is plaster of paris. +CaSO 4.H2O means two formula units of CaSO 4 share one molecule of water. +Uses - cast for healing fractures.1 +23 +2 +1 +21 +2chemistry-notes-CBSE class-10-chapter-1.txt +Chemical Reactions and Equations +Introduction to Chemical Reactions and Equations +Physical and chemical changes +Chemical change - one or more new substances with new physical and chemical properties +are formed. +Example: Fe(s)  +  CuSO 4(aq) →FeSO 4(aq) +Cu(s)  +       (Blue)                      (Green)        +Here, when copper sulphate reacts with iron, two new substances, i.e., ferrous sulphate and +copper are formed. +Physical change - change in colour or state occurs but no new substance is formed. +Example: Water changes to steam on boiling but no new substance is formed(Even though +steam and water look different when they are made to react with a piece of Na, they react +the same way and give the exact same products). This involves only change in state (liquid +to vapour).  +Observations that help determine a chemical reaction +A chemical reaction can be determined with the help of any of the following observations: +a) Evolution of a gas +b) Change in temperature +c) Formation of a precipitate +d) Change in colour +e) Change of state +Chemical reaction +Chemical reactions are chemical changes in which reactants transform into products by +making or breaking of bonds(or both) between different atoms. +Types of chemical reactionsTaking into consideration different factors, chemical reactions are grouped into multiple +categories. +Few examples are: +●Combination +●Decomposition +●Single Displacement +●Double displacement +●Redox +●Endothermic +●Exothermic +●Precipitation +●Neutralisation +Chemical Reactions and Equations I +Word equation +A  word equation is a chemical reaction expressed in words rather than chemical +formulas. It helps identify the reactants and products in a chemical reaction. +For example,  +Sodium + Chlorine → Sodium chloride +The above equation means: "Sodium reacts with chlorine to form sodium chloride."  +Symbols of elements and their valencies +A symbol is the chemical code for an element. Each element has one or two letter atomicchemistry-notes-CBSE class-10-chapter-1.txt +formulas. It helps identify the reactants and products in a chemical reaction. +For example,  +Sodium + Chlorine → Sodium chloride +The above equation means: "Sodium reacts with chlorine to form sodium chloride."  +Symbols of elements and their valencies +A symbol is the chemical code for an element. Each element has one or two letter atomic +symbol, which is the abbreviated form of its name. +Valency is the combining capacity of an element. It can be considered as the number of +electrons lost, gain or shared by an atom when it combines with another atom to form a +molecule. +Writing chemical equations +Representation of a chemical reaction in terms of symbols and chemical formulae of the +reactants and products is known as a chemical equation. +Zn(s) +dil.H2SO 4(aq) →ZnSO 4(aq) +H2(↑) + (Reactants)   (Products) +• For solids, the symbol is "(s)". +• For liquids, it is "(l)". +• For gases, it is "(g)".• For aqueous solutions, it is "(aq)". +• For gas produced in the reaction, it is represented by "(↑)". +• For precipitate formed in the reaction, it is represented by "(↓)". +Balancing of a Chemical Reaction +Conservation of mass +According to the law of conservation of mass, no atoms can be created or destroyed in a +chemical reaction, so the number of atoms for each element in the reactants side has to +balance the number of atoms that are present in the products side. +In other words, the total mass of the products formed in a chemical reaction is equal to the +total mass of the reactants participated in a chemical reaction. +Balanced chemical equation +The chemical equation in which the number of atoms of each element in the reactants side +is equal to that of the products side is called a balanced chemical equation. +Steps for balancing chemical equations +Hit and trial method: While balancing the equation, change the coefficients (the numbers in +front of the compound or molecule) so that the number of atoms of each element is same +on each side of the chemical equation.chemistry-notes-CBSE class-10-chapter-1.txt +is equal to that of the products side is called a balanced chemical equation. +Steps for balancing chemical equations +Hit and trial method: While balancing the equation, change the coefficients (the numbers in +front of the compound or molecule) so that the number of atoms of each element is same +on each side of the chemical equation.  +Short-cut technique for balancing a chemical equation +Example: +aCaCO 3+bH3PO 4→cCa 3(PO 4)2+dH2CO 3 +Set up a series of simultaneous equations, one for each element. +Ca: a=3c +C:   a=d +O:   3a+4b=8c+3d +H:   3b=2d +P:    b=2c +Let's set c=1 +Then a=3 and +d=a=3 +b=2c=2So a=3; b=2; c=1; d=3 +The balanced equation is +3CaCO 3+ 2H 3PO 4→Ca3(PO 4)2+ 3H 2CO 3 +Chemical Reactions and Equations II +Types of chemical reactions +Taking into consideration different factors, chemical reactions are grouped into multiple +categories. +Few examples are: +●Combination +●Decomposition +●Single Displacement +●Double displacement +●Redox +●Endothermic +●Exothermic +●Precipitation +●Neutralisation +Combination reaction +In a combination reaction, two elements or one element and one compound or two +compounds combine to give one single product. +H2+Cl2→ 2HCl +element + element → compound +2CO +O2→ 2CO 2 +compound + element → compound +NH 3+HCl →NH 4Cl +compound + compound → compound +Decomposition reaction +A single reactant decomposes on the application of heat or light or electricity to give two or +more products. +Types of decomposition reactions: +a. Decomposition reactions which require heat - thermolytic decomposition or thermolysis. +Thermal decomposition of HgO +b. Decomposition reactions which require light - photolytic decomposition or photolysis. +Photolytic decomposition of H2O2 +c. Decomposition reactions which require electricity - electrolytic decomposition or +electrolysis. +Electrolytic decomposition of H 2O +Displacement reaction +More reactive element displaces a less reactive element from its compound or solution.i)Zn(s) +CuSO 4(aq) →ZnSO 4(aq) +Cu(s)chemistry-notes-CBSE class-10-chapter-1.txt +Photolytic decomposition of H2O2 +c. Decomposition reactions which require electricity - electrolytic decomposition or +electrolysis. +Electrolytic decomposition of H 2O +Displacement reaction +More reactive element displaces a less reactive element from its compound or solution.i)Zn(s) +CuSO 4(aq) →ZnSO 4(aq) +Cu(s) +ii)Cu(s) + 2AgNO 3(aq) →Cu(NO 3)2(aq) + 2Ag (s) +Double displacement reaction +An exchange of ions between the reactants takes place to give new products. +For example, Al 2(SO4)3(aq) + 3Ca( OH)2(aq) → 2Al (OH)3(aq) + 3CaSO 4(s) +Precipitation reaction +An insoluble compound called precipitate forms when two solutions containing soluble salts +are combined.  +For example, Pb( NO 3)2(aq) + 2KI (aq) → 2KNO 3(aq) +PbI 2(↓)(s)(yellow ) +Redox reaction +Oxidation and reduction take place simultaneously. +Oxidation: Substance loses electrons or gains oxygen or loses hydrogen. +Reduction: Substance gains electrons or loses oxygen or gains hydrogen. +Oxidising agent - a substance that oxidises another substance and self-gets reduced. +Reducing agent - a substance that reduces another substance and self-gets oxidised. +Examples: +1.Fe(s) +CuSO 4(aq) →FeSO 4(aq) +Cu(s)       (Blue)                (Green) +Fe→Fe+2+ 2e −  (oxidation ) ; Fe - reducing agent. +Cu+2+ 2e − →Cu(s) (reduction ) ; Cu - oxidising agent. +2.ZnO +C→Zn+CO +ZnO reduces to Zn → reduction +C oxidises to CO → oxidation +ZnO - Oxidising agent +C - Reducing agent +Endothermic and exothermic reaction +Exothermic reaction - heat is evolved during a reaction. Most of the combination reactions +are exothermic. +Al+Fe2O3→Al2O3+Fe+heat +CH 4+ 2O 2→CO 2+ 2H 2O+heat +Endothermic - Heat is required to carry out the reaction. +6CO 2+ 6H 2O+Sunlight →C6H12O6+ 6O 2 +       Glucose +Most of the decomposition reactions are endothermic. +Corrosion +Gradual deterioration of a material, usually a metal, by the action of moisture, air or +chemicals in the surrounding environment. +Rusting:chemistry-notes-CBSE class-10-chapter-1.txt +are exothermic. +Al+Fe2O3→Al2O3+Fe+heat +CH 4+ 2O 2→CO 2+ 2H 2O+heat +Endothermic - Heat is required to carry out the reaction. +6CO 2+ 6H 2O+Sunlight →C6H12O6+ 6O 2 +       Glucose +Most of the decomposition reactions are endothermic. +Corrosion +Gradual deterioration of a material, usually a metal, by the action of moisture, air or +chemicals in the surrounding environment. +Rusting: +4Fe(s) + 3O 2(from  air) +xH 2O(moisture ) → 2Fe 2O3.xH 2O(rust) +Corrosion of copper: +Cu(s) +H2O(moisture ) +CO 2(from  air) →CuCO 3.Cu(OH)2(green ) +Corrosion of silver: +Ag(s) +H2S(from  air) →Ag2S(black) +H2(g) +Rancidity +It refers to oxidation of fats and oils in food that is kept for a long time. It gives foul smell +and bad taste to food. Rancid food causes stomach infection on consumption. +Prevention: +(i) Use of air-tight containers(ii) Packaging with nitrogen +(iii) Refrigeration +(iv) Addition of antioxidants or preservativesDOC-20240418-WA0021..txt +IntroductionAll living organisms have certain common characteristics such as breathing, growing, requiring nutrition, producing offspring, responding to stimuli, etc. that distinguish them from non-living things. There are certain vital processes that maintain homeostasis and proper functioning of the body, they are called life processes. These processes continue to occur even when we are sleeping or not performing any action. These processes are essential for all living organisms including plants and animals. These life processes are nutrition, photosynthesis, transportation, metabolism, respiration, reproduction and excretion.In this chapter, we will learn about the details of these processes occurring in plants, animals and human beings in particular.LifeEarth happens to be the only known planet having a life. There are beings who live, die and become part of nature again. The living organism can be differentiated from the inanimate entities on various parameters of life processes. +Life Process + +•The maintenance of living organisms is essential even if they are moving, resting or even sleeping.•The processes which together perform the function of maintenance of 'life' are called as life processes.•Nutrition, respiration, circulation, and excretion are examples of essential life processes.•In unicellular organisms, all these processes are carried out by a single cell.•In multicellular organisms, well-developed systems are present to carry out the processes. +To know more about Life Process, visit here. Students can refer to the short notes and MCQ questions along with a separate solution pdf of this chapter for quick revision from the links below:•Life Processes Short Notes•Life Processes MCQ Practice Questions•Life Processes MCQ Practice SolutionsDOC-20240418-WA0021..txt +To know more about Life Process, visit here. Students can refer to the short notes and MCQ questions along with a separate solution pdf of this chapter for quick revision from the links below:•Life Processes Short Notes•Life Processes MCQ Practice Questions•Life Processes MCQ Practice Solutions + +NutritionNutritionThe process of acquiring food that is needed for nourishment and sustenance of the organism is called nutrition.•There are two main modes of nutrition, autotrophic and heterotrophic.•Autotrophic nutrition is present in plants, algae and some bacteria. Organisms produce their own food using light energy or chemical energy by photosynthesis or chemosynthesis, respectively.•Heterotrophic nutrition is present in bacteria, fungi and animals. They derive energy from organic compounds. Such as animals eating plants or other animals for food.•Heterotrophic nutrition has subtypes such as holozoic, saprophytic and parasitic nutrition.To know more about Nutrition, visit here.Autotrophic NutritionIf an organism can nourish itself by making its own food using sunlight or chemicals such mode of nutrition is called as autotrophic nutrition.•Plants photosynthesize (use light energy) and are called photoautotrophs.•Few bacteria use chemicals to derive energy and are called chemoautotrophs. + +Photosynthesis•Photosynthesis is an important process by which food is formed.•The plants make food using sunlight and water, which provides nourishment to other organism and themselves.•Chlorophyll present in the green parts absorbs light energy.•This light energy is used to split water into hydrogen and oxygen.•Hydrogen is then used to reduce carbon dioxide into carbohydrates, typically glucose.•Chlorophyll is essential for photosynthesis and stomata to facilitate intake of carbon dioxide.The overall reaction occurring in photosynthesis is as follows:6CO2 + 6H2O → C6H12O6 + 6O2To know more about Photosynthesis, visit here.DOC-20240418-WA0021..txt +Stomata•Stomata are pores on the leaves that help in the exchange of gases.•They are mostly found on the underside of the leaf.•Each stoma is guarded by guard cells, which control the opening and closing of the pore.•The water content of the guard cells is responsible for their function. +To know more about Stomata, visit here.Saprophytic NutritionSome organisms feed on dead and decaying organic matter. This mode of nutrition is called saprophytic nutrition.•The food is partially digested outside the body and then it is absorbed.•E.g. Fungi are saprophytes.Parasitic NutritionSome organisms feed at the expense of another organism and in turn cause harm. This is called the parasitic mode of nutrition.•These parasites live on the body or in the body of a host organism and derive the nutrients directly from the body of the host.•E.g. Leech is an ectoparasite while Ascaris is an endoparasite. Cuscuta is a parasitic plant. + +Nutrition in Amoeba•Amoeba feeds by holozoic mode of nutrition.•It engulfs the food particle using pseudopodia, the process is called phagocytosis.•The engulfed food gets enclosed in a food vacuole.•As the food vacuole passes through the cytoplasm, digestion, absorption and assimilation take place.•When the food vacuole opens to outside, the egestion of undigested food takes place. + +To know more about Nutrition in Amoeba, visit here.Nutrition in Paramoecium•Paramoecium also exhibits holozoic nutrition.•However, they have cilia that help them to engulf the food through the oral groove.•A food vacuole is created enclosing the food.•It moves through the cytoplasm, the process is called cyclosis.•Food digested in the food vacuole is absorbed by the cytoplasm.•Undigested food is given out to a tiny pore called anal pore or cytopyge.DOC-20240418-WA0021..txt +Nutrition in Humans•Humans are omnivores, they can eat plant-based food as well as animal-based food.•Being more complex, humans have a very complicated nutrition system.•The digestive system has an alimentary canal and associated digestive glands, which together function to nourish the body.•There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and Egestion.•Four stages i.e. ingestion, digestion, absorption and egestion take place in the alimentary canal while assimilation of food takes place in the whole body.To know more about Nutrition in Humans, visit here.Alimentary Canal•The alimentary canal in humans is a long tube of varying diameter.•It starts with the mouth and ends with the anus.•Oesophagus, stomach, small intestine and large intestine are the parts of the alimentary canal. + +To know more about Alimentary Canal, visit here. MouthDOC-20240418-WA0021..txt +To know more about Alimentary Canal, visit here. Mouth + +•It is the opening of the alimentary canal and helps in the ingestion of food.•The buccal cavity which is present behind the mouth is also commonly referred to as the mouth.•The buccal cavity has teeth and a tongue.•The set of teeth helps in the mastication of food.•The tongue has taste buds on it and thus helps in tasting the food.•The salivary glands open also in the buccal cavity and pour saliva which initiates the process of digestion.Teeth•Teeth are the hard structures present in the buccal cavity.•They help us to cut, shear and masticate the food we eat.•The vertical section of a tooth shows four layers enamel, dentine, cement and dental pulp.•Enamel is the outermost, shiny, highly mineralized and the hardest part of the human body.•Dentine makes the bulk of the tooth and contains 70% inorganic salts.•Cement is present at the lining of a tooth and bony socket.•The dental pulp is the central soft part of a tooth and contains nerve endings, blood and lymph vessels along with connective tissue.•There are four types of teeth in humans, Incisors, canines, molars and premolars, each with a specific function.•Incisors cut the food, canines tear the food while molars and premolars crush it.•The dental formula in adult humans is 2:1:2:3. + +Oesophagus & StomachOesophagus•The swallowed food passes into the oesophagus.•It is a muscular tube, about 25 cm long, with a sphincter (valve/opening) at each end.•Its function is to transport food and fluid, after being swallowed, from the mouth to the stomach.•Food is pushed down by peristaltic movements.StomachDOC-20240418-WA0021..txt +Oesophagus & StomachOesophagus•The swallowed food passes into the oesophagus.•It is a muscular tube, about 25 cm long, with a sphincter (valve/opening) at each end.•Its function is to transport food and fluid, after being swallowed, from the mouth to the stomach.•Food is pushed down by peristaltic movements.Stomach + +•The stomach is a thick-walled bag-like structure.•It receives food from the oesophagus at one end and opens into the small intestine at the other end.•The inner lining of the stomach secretes mucous, hydrochloric acid and digestive juices.•Food is churned into a semi-solid mass in the stomach and is called chyme.•Enzymes present in the gastric juice break down the food.•Hydrochloric acid helps in the partial digestion of proteins and also kills harmful bacteria.•The mucus secreted by the wall of the stomach resists the action of HCl on itself.Small Intestine•The small intestine is the longest part of the alimentary canal, about 20 feet long in humans.•It has regions, duodenum, the region which follows the stomach, jejunum is the middle part and the ileum is the later region which continues further into the large intestine.•The internal surface of the small intestine is folded into finger-like projections called villi.•A common pancreatic duct from the pancreas and liver opens into the duodenum.•Most of the chemical digestion and absorption take place in the small intestine.Large Intestine•The large intestine in humans is about 5 feet long.•It has two regions, colon ( about 1.5 m) and rectum (10 cm in length in the adult).•The region of large intestine after ileum is called colon while the last part is called the rectum.•Colon has three regions as, ascending colon, transverse colon and descending colon.•At the base of the ascending colon, a small finger-like out-growth is seen and is called an appendix.•It houses many useful bacteria required for digestion of food. + +•Rectum opens to outside by anus.•The anus has internal and external anal sphincters.DOC-20240418-WA0021..txt +•Rectum opens to outside by anus.•The anus has internal and external anal sphincters. +PeristalsisA constant wave-like movement of the alimentary canal right from the oesophagus to the small intestine is called as peristalsis.•Muscles present in the wall of the alimentary canal are responsible for peristalsis.•This movement helps to push the food through the alimentary canal.To know more about Peristalsis, visit here.Digestive Glands•Several glands produce digestive juices that help in digestion of the food.•Salivary glands, Gastric glands, Liver, Gallbladder, Pancreas are few to name.•Salivary glands secrete saliva which initiates digestion in the mouth itself.•Gastric glands present in the wall of the stomach secrete hydrochloric acid and enzyme pepsin.•The liver secretes bile which is stored in the gallbladder. Bile helps in digestion of fats.•The pancreas secretes many digestive enzymes and its secretion is called as pancreatic juice. + +•Enzymes like trypsin, chymotrypsin, lipase, amylase are present in the pancreatic juice.Pancreas•The pancreas is a long, flat gland present behind the stomach in humans.•It is one of the major digestive glands and is of mixed nature i.e. endocrine as well as exocrine.•As an endocrine organ, it secretes two hormones called insulin and glucagon which maintain the blood sugar level.•As an exocrine gland, it secretes pancreatic juice which is nothing but a mixture of many digestive enzymes.•The digestive enzymes secreted by the pancreas include trypsin and chymotrypsin and proteases which digest proteins.•It also includes amylase which digests the starch content of the food.•Pancreatic lipases are the pancreatic enzymes that help in digestion of fats. +To know more about Pancreas, visit here.Holozoic NutritionThe mode of nutrition in which animals take their food as a whole is called as holozoic nutrition.DOC-20240418-WA0021..txt + +In holozoic nutrition, food passes through five steps as ingestion, digestion, absorption, assimilation and egestion.Physiology of Digestion•Mechanical digestion of food takes place in the buccal cavity where teeth masticate the food, saliva gets mixed and it turns into a bolus.•Digestion of starch starts in the buccal cavity itself, with the action of salivary amylase present in the saliva.•Salivary amylase converts starch into maltose.•In the stomach, the churning of food takes place due to the muscular contraction and relaxation of its wall. It breaks down the food into simpler substances.•Digestion of proteins starts in the stomach with the action of pepsin. Proteins are broken down into smaller fragments called peptide by the action of pepsin.•The bolus after mixing with gastric juice, turn into a fine soluble form known as the chyme.•Chyme enters into the small intestine where complete digestion takes place due to the action of various enzymes present in the pancreatic juice, bile and intestinal juice.•The digested food is completely absorbed by the villi and microvilli of the small intestine.•Undigested food then enters into the large intestine.•The colon is responsible for absorption of water and salts whereas rectum stores the undigested food temporarily before defaecation.To know more about Digestive System, visit here.Digestive System in Other Animals•Digestive systems in different animals vary in structure and function.•The structure of the digestive system depends on the food habits of the animal.•Alimentary canal in herbivores is long as the cellulose content of their plant-based diet takes a long time to digest.•On the other hand, the alimentary canal of carnivorous animals is comparatively shorter because meat gets digested faster.Anatomy of Digestive Tract•The alimentary canal in humans is approximately 30 feet (9m) long. It is also called the gastrointestinal tract.•It starts with the mouth and ends in the anus.•Between these two openings, the alimentary canal is a tube of varying diameter.•Oesophagus, stomach, small intestine (divided into three regions duodenum, jejunum and ileum) and large intestine(having two regions colon and rectum) are the parts of the alimentary canal.•Salivary glands, pancreas and liver act as major digestive glands.•Glands present in the wall of the stomach and small intestine also contribute to the digestion of food.DOC-20240418-WA0021..txt +Role of HCl•Hydrochloric acid in the stomach is secreted by the gastric glands present in its wall.•the pH of the gastric acid is usually between 1.5 to 3.5•This acid serves the following functions:1.Converts inactive pepsinogen and pro-rennin into active pepsin and rennin respectively.2.Provides an acidic medium for protein digestion.3.Kills bacteria entered through food and prevents infection.4.Prevents putrefaction of food in the stomach.•A thick layer of mucus secreted by the mucous glands of the stomach prevents itself from the action of gastric acid.•Excess acid damages gastric mucosa and causes gastric and duodenal ulcers.Salivary Glands•Salivary glands are the exocrine glands that secrete saliva and through a system of ducts, it is poured into the mouth.•In humans, three major pairs of salivary glands are present, parotid, submandibular and sublingual.•In healthy individuals between 0.5 to 1.5 litres of saliva is produced per day.•Saliva serves the following functions in the oral cavity:1.It lubricates and protects the soft and hard tissues of the oral cavity2.It also gives protection from dental caries3.Saliva prevents microbial growth in the oral cavity.4.Saliva can encourage soft tissue repair by decreasing clotting time and increasing wound contraction5.Saliva contains the enzyme amylase that hydrolyses starch into maltose and dextrin. Hence saliva allows digestion to occur before the food reaches the stomach6.Saliva acts as a solvent in which solid particles can dissolve in and enter the taste buds located on the tongue.DOC-20240418-WA0021..txt +Heterotrophic NutritionWhen an organism depends on others for food, such a mode of nutrition is called as a heterotrophic mode of nutrition.•These organisms depend on autotrophs for their nutritional requirements.•E.g. Animals which eat plants as their food are called herbivores.•Animals which eat other animals as their food are called carnivores.•Holozoic, saprophytic and parasitic nutrition are all types of heterotrophic nutrition.To know more about Heterotrophic Nutrition, visit here.Glandular Epithelium•Many small glands present in the inner layer of the stomach and intestine take part in the digestion of food.•These glands are present in the epithelial lining of the stomach and intestine.DOC-20240418-WA0021..txt +•The glands present in different regions of the stomach are called gastric glands.•They are responsible for the secretion of mucus, hydrochloric acid and enzymes like pepsinogen.•The glands present in the epithelial lining of the small intestine and large intestine are called intestinal glands.•Glands of the small intestine are responsible for the secretion of intestinal juice also called succus entericus.•Intestinal juice contains hormones, digestive enzymes, alkaline mucus, and substances to neutralize hydrochloric acid coming from the stomach.•Intestinal juice completes the digestion started by the pancreatic juice.•Glands of the large intestine are associated with the absorption of water and electrolytes.Villi and Micro Villi•Complete digestion and absorption of food take place in the small intestine.•Pancreatic juice coming from the pancreas, bile from the liver and intestinal juice secreted by the intestinal glands complete the digestion of food material.•All the digested nutrients are absorbed by the long finger-like projections present in the ileum of the small intestine.•These small finger-like projections of the inner wall of intestine are called as villi (singular: villus).•Each villus has its cell membrane of the lumen side again folded into microscopic processes, called microvilli.•Villi increase the internal surface area of the intestinal walls making available a greater surface area for absorption.•Digested nutrients pass into the semipermeable villi through diffusion.•Villi also help in chemical digestion of food by secreting digestive enzymes. + + LiverDOC-20240418-WA0021..txt +Liver + +•The liver is the largest and major digestive gland of humans•Liver, in humans, is located in the upper right-hand portion of the abdomen.•This organ is dark reddish-brown in colour due to an extensive blood supply.•Some of the important functions of the liver are as follows:1.It secretes bile that helps in digestion.2.It filters the blood coming from the digestive tract before passing it to the rest of the body.3.It detoxifies various metabolites and antidote.4.The liver makes proteins important for blood clotting and other functions.5.It stores and releases glucose as needed.6.It processes haemoglobin, from the dead and worn out RBCs, for the iron content (the liver stores iron).7.Conversion of harmful ammonia to urea takes place in the liver.To know more about Liver, visit here.Digestive JuicesDOC-20240418-WA0021..txt +•Pancreatic juice, bile and intestinal juice (succus entericus) are collectively called digestive juices.•A common duct from digestive glands pours the secretions into the duodenum.•Chyme enters the small intestine where complete digestion takes place due to the action of various enzymes.•In the duodenum, the acidity of chyme is turned to alkalinity by the action of bile coming from the liver. This is necessary for pancreatic enzyme action.•Bile also emulsifies the fats into smaller globules.•Pancreatic and intestinal amylases break down carbohydrates into glucose.•Trypsin and chymotrypsin are the proteases responsible for the breakdown of proteins finally into amino acids.•Lipase is the enzyme which acts on the emulsified fats and breaks them down into glycerol and fatty acids.Water Absorption in Large Intestine•The large intestine is not involved in the digestion of food or absorption of nutrients.•The major function of the large intestine is to absorb water from the remaining indigestible food matter and make the stool solid.•The large intestine also helps in the absorption of vitamins made by bacteria that normally live in the large intestine.•The innermost layer of the large intestine also acts as a barrier and protects from microbial infections and invasions.•Rectum stores the undigested food temporarily until defecation.RespirationIntroduction to Respiration•Respiration broadly means the exchange of gases.•Animals and plants have different means of exchange of gases.•At a cellular level, respiration means the burning of the food at the for generating the energy needed for other life processes.•Cellular respiration may take place in the presence or absence of oxygen.DOC-20240418-WA0021..txt +To know more about Respiration, visit here.Respiration in Humans•The human respiratory system is more complex and involves breathing, exchange of gases and cellular respiration.•A well defined respiratory system helps breathing and exchange of gases.•Breathing involves the inhalation of oxygen and exhalation of carbon dioxide.•The gaseous exchange takes place in the lungs and oxygen is supplied to all cells of the body.•Cellular respiration takes place in each and every cell.Respiratory System•The human respiratory system involves the nose, nasal cavities, pharynx, larynx, trachea/windpipe, bronchi, bronchioles and alveoli.•Bronchioles and alveoli are enclosed in a pair of lungs.•The rib cage, muscles associated with the rib cage and diaphragm, all help in inhalation and exhalation of gases.•Exchange of gases takes place between an alveolar surface and surrounding blood vessels.•Alveoli provide a large surface area for exchange of gases.To know more about Respiratory System, visit here.Physiology of Respiration•Breathing in humans is facilitated by the action of internal intercostal and external intercostal muscles attached to the ribs and the diaphragm.•When the dome-shaped diaphragm contracts and becomes flattened and the rib cage is expanded due to the action of intercostal muscles, the volume of the lungs increases, pressure there drops down and the air from outside gushes in. This is inhalation.DOC-20240418-WA0021..txt +•To exhale, the diaphragm relaxes, becomes dome-shaped again, chest cavity contracts due to the action of intercostal muscles, the volume inside the lungs decreases, pressure increases and the air is forced out of the lungs.•Inhaled air increases the concentration of oxygen in the alveoli,  so oxygen simply diffuses into the surrounding blood vessels.•Blood coming from cells has more concentration of carbon dioxide than outside air and thus carbon dioxide simply diffuses out of the blood vessels into the alveoli.•Thus, breathing takes place due to the combined action of intercostal muscles and diaphragm while the exchange of gases takes place due to simple diffusion. + Inhalation and Exhalation•The process of taking in air rich in oxygen is called inhalation.•Similarly, the process of giving out air rich in carbon dioxide is called exhalation.•One breath comprises one inhalation and one exhalation.•A person breathes several times in a day.•The number of times a person breathes in one minute is termed as his/her breathing rate.To know more about Inhalation and Exhalation, visit here.Diffusion + +Diffusion is the movement of molecules from high concentration area to the low concentration area without spending any energy.DOC-20240418-WA0021..txt +Diffusion is the movement of molecules from high concentration area to the low concentration area without spending any energy. + Cellular RespirationCellular respiration is set of metabolic reactions occurring inside the cells to convert biochemical energy obtained from the food into a chemical compound called adenosine triphosphate (ATP).•Metabolism refers to a set of chemical reactions carried out for maintaining the living state of the cells in an organism. These can be divided into two categories:•Catabolism – the process of breaking molecules to obtain energy.•Anabolism – the process of synthesizing all compounds required by the cells.•Therefore, respiration is a catabolic process, which breaks large molecules into smaller ones, releasing energy to fuel cellular activities.•Glycolysis, Krebs cycle and electron transport chain are the important processes of the cellular respiration. + + To know more about Cellular Respiration, visit here.Aerobic RespirationAerobic respiration is a process in which the food i.e. glucose is converted into energy in the presence of oxygen.•The general equation of aerobic respiration as a whole is as given below-Glucose + oxygen ⇒ Carbon dioxide + Water + Energy•This type of respiration takes place in animals, plants and other living organisms.Respiration in Lower Animals•Lower animals lack a sophisticated respiratory system like lungs, alveoli etc.•Respiration in them takes place by simple exchange mechanisms.•Animals like earthworms take in gases through their skin.•Fishes have gills for gaseous exchange.•Insects have a tracheal system, which is a network of tubes, through which air circulates and gaseous exchange takes place.•Frogs breathe through their skin when in water and through their lungs when on land.DOC-20240418-WA0021..txt +Respiration in Muscles•Respiration in muscles can be anaerobic when there is not enough oxygen.•Glucose gets broken down into carbon dioxide and lactic acid.•This results in the accumulation of lactic acid that makes the muscles sore.•This type of anaerobic respiration is also known as lactic acid fermentation.ATP•It is the energy currency of the cell.•ATP stands for Adenosine Tri-Phosphate.•This molecule is created as a result reactions like photosynthesis, respiration etc.•The three phosphate bonds present in the molecule are high-energy bonds and when they are broken, a large amount of energy is released.•Such released energy is then used for other metabolic reactions. + + Respiration in Plants•Unlike animals and humans, plants do not have any specialized structures for gaseous exchange•They have stomata (present in leaves) and lenticels (present in stems) which are involved in the exchange of gases.•Compared to animals, plant roots, stems, and leaves respire at a very lower rate. + +To know more about Respiration in Plants, visit here.Transpiration +•Transpiration is a biological process in which water is lost in the form of water vapour from the aerial parts of the plants.•This process occurs mainly through the stomata where the exchange of gases (oxygen and carbon dioxide) occurs.•Transpiration helps in the transportation of water from roots to upper parts of plants and this is explained by 'transpirational pull theory'.•Loss of water, especially from leaves, acts as a straw effect and pulls water upwards from roots.•Transpiration also acts as an excretory mechanism in plants as it helps to get rid of excess water.To know more about Transpiration, visit here.Why Do We Need LungsDOC-20240418-WA0021..txt +•In unicellular organisms like an amoeba exchange of gases takes place through a general body surface by osmosis.•In lower animals like an earthworm, the gaseous exchange takes place through their moist skin.•The requirement for oxygen is sufficiently met in these ways.•But as the animal starts becoming more and more complex, for example, humans, the requirement of oxygen cannot be met alone by diffusion.•Moreover, diffusion will not be able to supply oxygen to the deep-seated cells.•This difficulty has led to the evolution of a more complex mechanism of gaseous exchange and that is the development of lungs.•The alveoli present in the lungs provide a large surface area required for the necessary gas exchange.Read more: Facts about LungsTransportation in Human Beings + +Transportation•All living organisms need a few necessary components like air, water, and food for their survival.•On a regular basis, animals ensure these elements by breathing, drinking and eating.•The required elements are transported to their body cells and tissues by a  transportation system.•In plants, the vascular tissue is responsible for transporting the substances.Transportation in Humans•Transportation in humans is done by the circulatory system.•The circulatory system in humans mainly consists of blood, blood vessels and the heart.•It is responsible for the supply of oxygen, and nutrients, and the removal of carbon dioxide and other excretory products.•It also helps to fight infections. +To know more about Transportation in Animals and Plants, visit here.Heart + +•The muscular organ which is located near the chest slightly towards the left in the thoracic region.•The heart is the main pumping organ of the body.•The human heart is divided into four chambers which are involved in the transportation of oxygenated and deoxygenated blood.•The upper two chambers are called atria whereas the lower two chambers are called as ventricles.DOC-20240418-WA0021..txt +•The muscular organ which is located near the chest slightly towards the left in the thoracic region.•The heart is the main pumping organ of the body.•The human heart is divided into four chambers which are involved in the transportation of oxygenated and deoxygenated blood.•The upper two chambers are called atria whereas the lower two chambers are called as ventricles. + +To know more about Human Heart, visit here.•The flow of blood through the heart is as follows: +Blood Vessels•Blood vessels carry blood throughout the body.•There three types of blood vessels; arteries, veins and blood capillaries.•Arteries carry oxygenated blood and veins carry deoxygenated blood.•Gaseous exchange takes place between blood and cells at capillaries.Difference between Arteries and Veins + + Blood PressureThe pressure exerted by the blood when it flows through the blood vessels is called blood pressure.•There are two different variants of blood pressure; systolic and diastolic blood pressure.•The pressure exerted on the walls of arteries when the heart is filling with blood is called diastolic pressure. It constitutes the minimum pressure on arteries.•The normal range of diastolic blood pressure should be 60 – 80 mm Hg.•The pressure exerted on the walls of arteries when the heart is pumping the blood is called systolic pressure. It constitutes the maximum pressure applied to the arteries.•The normal range of systolic blood pressure should be 90 – 120 mm Hg.To know more about Blood Pressure, visit here.Bleeding•Bleeding occurs when the blood vessels rupture.•Bleeding is stopped by the platelets that help in the clotting of blood at the site of the injury.•Blood Clotting is the process of forming a clot in order to prevent excess loss of blood from the body.•It is a gel-like mass which is formed by the platelets and a fibre-like protein in the blood.DOC-20240418-WA0021..txt +Double Circulation•In the human body, blood circulates through the heart twice.•Once it goes through the heart during pulmonary circulation and second time during systemic circulation.•Hence, circulation in human beings is called double circulation. + +To know more about Double Circulation, visit here.Transportation in PlantsTransportation in Plants•Transportation is a vital process in plants.•The process involves the transportation of water and necessary nutrients to all parts of the plant for its survival.•Food and water transportation takes place separately in plants.•Xylem transports water and phloem transports food. + To know more about Transportation in Plants, visit here.Phloem + +•The phloem is responsible for translocation of nutrients and sugar like carbohydrates, produced by the leaves to areas of the plant that are metabolically active.•Sieve tubes, companion cells, phloem fibres, and phloem parenchyma cells are the components of this tissue•The flow of material through phloem is bidirectional. + Translocation•Transport of food in the plant through phloem via a process such as mass flow is called as translocation.•Photosynthates i.e. sugars and organic molecules such as amino acids, organic acids, proteins and inorganic solutes like potassium, magnesium, nitrate, calcium, sulfur and iron from source tissues (mature leaves) to the sink cells (areas of growth and storage) are transported through the phloem.•Material like sucrose is loaded from leaves to phloem using the energy of ATP.•Such a transfer increases the osmotic pressure causing the movement of water from nearby cells into phloem tissue and the material gets transported through the phloem.•The same pressure is also responsible for the transfer of substances from phloem to tissues where food is required.•Thus the bulk flow of material through phloem takes place in response to an osmotically generated pressure difference.DOC-20240418-WA0021..txt +Xylem•Xylem tissue transports water in plants from root to all other parts of the plant.•Xylem tissue is made up tracheids, vessels, xylem fibres and xylem parenchyma.•The flow of water and minerals through xylem is always unidirectional. + +Root Pressure•Conduction of water through the xylem, from roots to upper parts of plants, is due to many forces acting together.•One of the forces responsible for this is root pressure.•Root pressure is osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves.•Root pressure helps in the initial transport of water up the roots.DOC-20240418-WA0021..txt +To know more about Root Pressure, visit here.Transport of Water•Water is absorbed by the roots and is transported by xylem to the upper parts of the plant.Imbibition, osmosis, root pressure and transpiration are the forces that contribute towards the upward movement of water, even in the tallest plants.•Imbibition is a process in which water is absorbed by the solids. E.g. seeds take up water when soaked.•Osmosis is a process where water moves from the area of its lower concentration to the area of its higher concentration.•At the roots, the cells take up ions by an active process and this results in the difference of concentration of these ions.•It leads to movement of water, in the root cells, by osmosis.•This creates a continuous column of water that gets pushed upwards. This is root pressure.•Transpiration contributes to the upward movement of water by creating a staw effect.•It pulls the water column upwards as there is a continuous loss of water from leaves.•All these forces act together for water transport through the xylemExcretion in HumansExcretionExcretion is the process of removal of metabolic waste material and other non-useful substances.•Organisms like animals have an advanced and specialized system for excretion.•But plants lack a well-developed excretory system like that in animals.•They do not have special organs for excretion and thus excretion in plants is not so complex.Excretion in Unicellular Organisms•In unicellular organisms such as amoeba and bacteria, the waste product is removed by simple diffusion through the general body surface.•Unicellular organisms like the amoeba, and paramecium excrete excess through tiny organelles called contractile vacuoles.•Undigested food in unicellular animals is excreted when the food vacuole merges with the general body surface and opens to the outside.Excretory System of Humans•The excretory system in humans includes◦a pair of kidneys,◦a pair of ureters,DOC-20240418-WA0021..txt +◦a urinary bladder and◦urethra.•It produces urine as a waste product. +To know more about Human Excretory System, visit here.Kidneys•Paired kidneys are the main excretory organs of the body.•They are basically the filtration units of the human body.•Each kidney is made up of many tiny filtration units called nephrons.•Kidneys perform crucial functions like:1.Filtering waste materials, medications, and toxic substances from the blood.2.Regulation of osmolarity i.e. fluid balance of the body.3.Regulation of ion concentration in the body.4.Regulation of pH.5.Regulation of extracellular fluid volume.6.Secreting hormones that help produce red blood cells, promote bone health, and regulate blood pressureNephronNephrons are the structural and functional unit of kidney.•Each kidney has millions of nephrons and it forms the basic structural and functional unit of the kidney. + +•Each nephron has two parts: Malpighian body and renal tubule.•Malpighian body is made up of cup-like structure called Bowman's capsule which encloses a bunch of capillaries called glomerulus.•They together filter waste materials along with many useful substances.•Renal tubule has regions called proximal convoluted tubule, Loop of Henle and distal convoluted tubule.•These regions absorb back useful substances into the blood and also filter remaining waste substances.•The output from nephrons is called urine. + Haemodialysis◦When the kidneys fail, it results in a lot of complications and to compensate this situation a technology called dialysis has been developed.◦It uses a machine filter called a dialyzer or artificial kidney.◦This is to remove excess water and salt, to balance other electrolytes in the body and remove waste products of metabolism. + +◦Blood from the body is removed and flowed through a series of tubes made up of a semipermeable membrane.◦A dialysate flows on the other side of the membrane, which draws impurities through the membrane.DOC-20240418-WA0021..txt +◦Blood from the body is removed and flowed through a series of tubes made up of a semipermeable membrane.◦A dialysate flows on the other side of the membrane, which draws impurities through the membrane. +Excretion in Plants•The cellular respiration, photosynthesis, and other metabolic reactions produce a lot of excretory products in plants.•Carbon dioxide, excess water produced during respiration and nitrogenous compounds produced during protein metabolism are the major excretory products in plants.•Plants produce two gaseous waste products i.e. oxygen during photosynthesis and carbon dioxide during respiration. + +•Excretion of gaseous waste in plants takes place through stomatal pores on leaves.•Oxygen released during photosynthesis is used for respiration while carbon dioxide released during respiration is used for photosynthesis.•Excess water is excreted by transpiration.•Organic by-products generated by the plant are stored in different forms in different parts.•The gums, oils, latex, resins, etc. are some waste products stored in plant parts like barks, stems, leaves, etc.•Eventually, plants shed off these parts.•Few examples of the excretory products of plants are oil produced from orange, eucalyptus, jasmine, latex from the rubber tree, papaya tree, and gums from acacia.•Sometimes plants even excrete into the soil.  +To know more about Excretion in Plants, visit here.Also Check:•CBSE Class 10 Chapter 5 Periodic Classification of Elements Notes•CBSE Class 10 Science Chapter 7 Control and Coordination Notes•NCERT Solutions for Class 10 Science Chapter 6 Life Processes•NCERT Exemplar Class 10 Science Solutions for Chapter 6 - Life Processes•Real Numbers Class 10 Notes: Chapter 1•CBSE Class 10 History Notes Chapter 1 - The Rise of Nationalism in EuropeFrequently Asked Questions on Life ProcessesDOC-20240418-WA0021..txt +Q. The instrument used for measuring blood pressure is called?Ans. A sphygmomanometer is an instrument used for measuring blood pressure.Q. The phloem tissue in plants is responsible for doing which function?Ans. Phloem is the vascular tissues that is responsible for the transport of substances in plantsQ. Why aerobic respiration produces more usable chemical energy than fermentation?Ans. Aerobic respiration produces more usable chemical energy in the form of ATPs than fermentation because aerobic respiration involves the complete oxidation of glucose and the release of carbon dioxide and water as end products.Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt + 1 + + +Revision Not es +Class 10 Science +Chapter 13 - Magnetic Effects of Electric Current + +● Introduction: +- A magnet is a material that has the ability to attract metals such as iron, +nickel, cobalt, and steel. There are two poles to a magnet: north and +south. +- When liberated, the two poles pursue the earth's north and south poles. +Each component becomes a magnet when broken into parts. + +● Magnetic Field : +- A magnetic field is the area around a magnet where its influence can be +felt by any other magnetic element. +- The magnetic field is measured in Tesla or +2Weber/m units. +- Lines of Magnetic Fields +- Externally, magnetic field lines exit the north pole of a magnet and enter +the South Pole, forming closed loops. +- At the poles, where the magnetic field strength is greatest, magnetic +field lines are nearest. There are no magnetic f ield lines that cross one +other. +- The tangent at a place indicates the direction of the magnetic field at +that point. + +● Natural Magnet : +- Magnetite or Lodestone ( +34Fe O ), a naturally occurring black iron ore, +is a natural magnet. + +● Oersted’s Experiment: + + + 2 + + +- The needle has been deflected, indicating that an electric current has +caused a magnetic effect across the copper wire. +- As a result, we can say that electricity and magnetism are intertwined. + +● Magnet in a Magnetic Field: +- When a magnet is placed in a magnetic field, it aligns itself along the +field lines with the North Pole facing the magnetic field's direction of +travel. +- Due to the contents of the earth, a magnetic field exists on its surface, +causing it to behave like a m agnet. As a result, a magnetic needle is +employed to determine the direction on the earth's surface. + +● Magnetic Field around a Current Carrying Straight Conductor: + + + +When the current in the copper wire is altered, the needle deflection variesMagnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +travel. +- Due to the contents of the earth, a magnetic field exists on its surface, +causing it to behave like a m agnet. As a result, a magnetic needle is +employed to determine the direction on the earth's surface. + +● Magnetic Field around a Current Carrying Straight Conductor: + + + +When the current in the copper wire is altered, the needle deflection varies +as well. In reality, as the current rises, the deflection rises with it. +It means that when the current through the wire increases, the magnitude +of the magnetic field produced at a given spot grows. + +● Magnetic Field around a Current Carrying Circular Conductor: + + + + + + + + 3 + + + + +A current -carrying wire's magnetic field at a particular place is directly +proportional to the current flowing through it. +The field produced by a circular coil with n tu rns is n times larger than that +produced by a single turn. + +● Magnetic Field Due To a Solenoid: +A solenoid is a coil comprising several circular turns of insulated copper +wire wrapped tightly in the shape of a cylinder. + + + +A solenoid's magnetic field lines ar e seen in the diagram below. The +solenoid's one end acts as a magnetic north pole, while the other acts as a +magnetic south pole. +Pole: +Inside the solenoid, the field lines are in the shape of parallel straight lines. +This means that the magnetic field ins ide the solenoid is the same at all +places. That means, the field inside the solenoid is uniform. + + 4 + + +● Rules for Determining Direction of Magnetic Field: +- The direction of the curled fingers points in the direction of the magnetic +field if a straight conductor is clutched in the palm of the right hand with +the thumb pointing along the path of current flow. +- For circular conductors, use the right hand thumb ru le. +- The thumb points in the direction of the magnetic field if the circularMagnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +- The direction of the curled fingers points in the direction of the magnetic +field if a straight conductor is clutched in the palm of the right hand with +the thumb pointing along the path of current flow. +- For circular conductors, use the right hand thumb ru le. +- The thumb points in the direction of the magnetic field if the circular +current's direction matches with the curled fingers' direction. + + + +● The cork screw rule of Maxwell: +If the current through a conductor is represented by the direction of linear +motion of a cork screw, then the magnetic field is represented by the +direction of rotation of the cork screw. + + +● Ampere’s swimming rule: +If a guy swims along a current -carrying w ire with his face constantly facing +the magnetic needle, current entering his feet and exiting his head, the +magnetic needle's North Pole will always be deflected towards his left +hand. + + + 5 + + + + +● Magnetizing a Material: +The material can exhibit magnetic properties once it has been magnetised. + +● Permanent Magnets: +A permanent magnet is one that retains its magnetic properties after it has +been magnetised. This is a property of steel. + +● Electromagnets and Their Applications: +- When a piece of magnetic material, such as soft iron, is placed inside +the coil, a strong magnetic field produced inside the solenoid can be +used to magnetise it. +- An electromagnet is a magnet that has been formed in this way. +- Electric bells, loudspeakers , telephone diaphragms, and electric fans all +use electromagnets. +- Cranes also employ massive electromagnets to transport large loads. + +● Force on Current Carrying Conductor in a Magnetic Field: + + + + + + + + + + 6 + + + +When a current -carrying conductor is put in a magnetic field, it is subjected +to a force. When the current in the conductor is reversed, the direction of +force is reversed as well.Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +- Cranes also employ massive electromagnets to transport large loads. + +● Force on Current Carrying Conductor in a Magnetic Field: + + + + + + + + + + 6 + + + +When a current -carrying conductor is put in a magnetic field, it is subjected +to a force. When the current in the conductor is reversed, the direction of +force is reversed as well. + +● Fleming’s Left Hand Rule: + + +When the thumb, forefinger, and middle finger of the left hand are held +perpendicular to each other, with the forefinger pointing in the direction of +the magnetic field and the middle finger pointing in the direction of the +current, the thumb points in the direction of the force exerted on the +conduct or, according to Fleming's left hand rule. + +● Electric Motor : +A device that converts electrical energy into magnetic energy is known as +an electric motor. + +● DC Motor: +Principle: Torque acts on a rectangular coil carrying electricity when it is +put in a magnetic field, causing it to revolve continually. +When the coil spins, the shaft connecting to it rotates as well, allowing it +to perform mechanical tasks. + + 7 + + +● Construction and Workin g: +Parts of a DC Motor + + +● Armature: +A rectangular coil of insulated copper wire wound on a soft iron core makes +up a D.C. motor. The armature is made up of this coil coiled on a soft iron +core. The coil is positioned between the cylindrical concave poles of a +magnet and is mounted on an axle. + +● Commutator: +A commutator is a device that reverses the direction of current flow. A +commutator is a copper ring that is divided into two sections, C1 and C2. +The split rings are installed on the motor's axle and are shielded from one +another. These rings are attached to the coil's two ends. They spin in time +with the coil. A battery is linked to the commutator rings. The cables fromMagnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +● Commutator: +A commutator is a device that reverses the direction of current flow. A +commutator is a copper ring that is divided into two sections, C1 and C2. +The split rings are installed on the motor's axle and are shielded from one +another. These rings are attached to the coil's two ends. They spin in time +with the coil. A battery is linked to the commutator rings. The cables from +the batteries are attached to the brushes, which are in touch with the rings, +rather than the rings themselves. + +● Brushes: +- Brushes are two thin strips of carbon that press on the two split rings, +and the split rings revolve between them. +- A D.C. source is used to power the carbon brushes. + +● The Operation of a DC Motor: +When the coil is turned on, it creates a magnetic field surrounding the +armature. Rotation is caused by the left side of the armature being pushed +away from the left magnet and attracted towards the right. + + + + + 8 + + + +The brushes lose contact with the commutator as the coil turns through +90 +, and the current stops flowing through the coil. +The coil, on the other hand, continues to turn due to its own momentum. +When the coil passes past +180 , the sides are switched. As a result, +commutator ring C1 now contacts brush B2, whereas commutator ring C2 +contacts brush B1. As a result, the current keeps flowing in the same +direction. + +● The efficiency of the DC Motor Increases by: +- Increa sing the coil's number of turns. +- Increasing the current's strength. +- Increasing the coil's cross -sectional area. +- Increasing the radial magnetic field's strength. + +● Electromagnetic Induction (EMI): +Electromagnetic induction is a phenomena in which an emf or current is +induced in a conductor as a result of a change in the magnetic field around +the conductor. + + +The English physicist Michael Faraday was the first to demonstrate that a +magnet may generat e a current.Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +- Increasing the radial magnetic field's strength. + +● Electromagnetic Induction (EMI): +Electromagnetic induction is a phenomena in which an emf or current is +induced in a conductor as a result of a change in the magnetic field around +the conductor. + + +The English physicist Michael Faraday was the first to demonstrate that a +magnet may generat e a current. + + 9 + + +He tested this by moving a magnet in front of a coil of wire linked to a +galvanometer. +He noticed a deflection in the galvanometer, indicating that it had been +induced by a current. +Induced current is the current generated by the relative moti on of the coil +and the magnet. +Electromagnetic induction is a phenomena in which an emf or current is +induced in a conductor as a result of a change in the magnetic field around +the conductor. By moving a bar magnet in and out of a coil of wire, Faraday +came to a few conclusions. + +● Experiment: + + +● Observation: +The current is induced in the coil due to the relative motion between the +magnet and the coil, as indicated by the deflection in the galvanometer. + + + + 10 + + +● Observation: +When the identical pole of the magnet is moved in the other direction, the +deflection in the galvanometer is reversed. + + + +● Observation: +The galvanometer pointer returns to zero, indicating that the deflection in +the galvanometer will remain as long as the magnet and coil are in relative +motion. + + + +● Observation: +When the opposite pole is moved in the same direction, the deflection in +the galvanometer is reversed. + + + + + + + 11 + + + + +● Observation: +The number of turns in the coil affects the deflection in the galvanometer; +the more turns in the coil, the higher the deflection. Because the magnetic +field travels around each loop of wire in the coil, the magnetic field changesMagnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +the galvanometer is reversed. + + + + + + + 11 + + + + +● Observation: +The number of turns in the coil affects the deflection in the galvanometer; +the more turns in the coil, the higher the deflection. Because the magnetic +field travels around each loop of wire in the coil, the magnetic field changes +more as the number of coi ls increases. In and out of the coil, the magnet +moves quicker. If the magnet is moved faster, the deflection is greater. That +is, when the magnet moves quicker, the rate at which the current is induced +increases. + +● Mutual Induction: +- Mutual induction is the phenomenon of producing induced emf in one +coil as a result of a current shift in an adjacent coil. To further +comprehend this, let us conduct an experiment. +- As indicated, place two coils P and S near to one other. +- Connect the primary coil P to a battery and a key, and the secondary +coil S to a sensitive galvanometer G. +- The galvanometer shows a deflection whenever the key is pressed or +released. By pressing and releasing the key, you can now see the +deflection of the galvanometer needle. Because the curren t passing +through the first coil causes a current in the secondary coil, the needle +deflects. + + + + + + + + + 12 + + + + +● What Causes Mutual Induction? +- When you hit the key K, current begins to flow through the coil P, +increasing the magnetic flux associated with P. +- Because S is so close to P, the magnetic flux associated with S increases +as well. Induced emf and, as a result, induced current are produced in +S. +- According to Lenz's law, the arrow marked 1 indicates the direction of +induced current in S. + + + +- When the key is released, the magnetic flux associated with the coils +drops, causing induced current to flow in the direction indicated by the +- + 13Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +as well. Induced emf and, as a result, induced current are produced in +S. +- According to Lenz's law, the arrow marked 1 indicates the direction of +induced current in S. + + + +- When the key is released, the magnetic flux associated with the coils +drops, causing induced current to flow in the direction indicated by the +- + 13 + + +arrow marke d 2. The development of induced emf in the secondary coil +during the make or break of current in the primary coil is known as +mutual induction. + +● Rules for Determining the Direction of Induced Current: +- Fleming's Right Hand Rule can be used to determine the direction of +induced current. + + +- Stretch the right hand's forefinger, middle finger, and thumb such that +they are all perpendicular to one another. The direction of the magnetic +field is shown by the forefinger, the direction of conductor motion is +indicate d by the thumb, and the direction of induced current in the +conductor is indicated by the middle finger. +- The above -mentioned phenomenon is used to power the electric +generator. + +● The Right Hand Rule of Fleming: +- Fleming's Right Hand Rule - Stretch the right hand's forefinger, middle +finger, and thumb such that they are all perpendicular to one other. +- The direction of the magnetic field is shown by the forefinger, the +direction of conductor motion is indicated by t he thumb, and the +direction of induced current in the conductor is indicated by the middle +finger. + + + + + + + + + 14 + + + + +● Electric Generator (AC): +- Mechanical energy is converted into electrical energy by the electric +generator. +- DC and AC generators are the two types of generators: +- A cycle dynamo and a car dynamo are both examples of DC generators. +They generate DC. + +● Generators - Generators - Generato rs - Generators - Generators In powerMagnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt + 14 + + + + +● Electric Generator (AC): +- Mechanical energy is converted into electrical energy by the electric +generator. +- DC and AC generators are the two types of generators: +- A cycle dynamo and a car dynamo are both examples of DC generators. +They generate DC. + +● Generators - Generators - Generato rs - Generators - Generators In power +plants and industries, generators or alternators are utilised to generate AC. + +● The Basics of an AC Generator: +When a straight conductor is rapidly moved in a magnetic field, it induces +a current in the conductor. It is based on the electromagnetic induction +phenomena. + +● Construction: +The AC Generator's Main Components: +A magnet with concave cylindrical poles, an armature, and a current +collecting system make up an AC generator. +Slip rings and brushes make up the present collection system. + + + + + + + + + 15 + + + + +- Armature is a soft iron core around which a coil of insulated copper wire +with a large number of turns is coiled. Magnetic poles are cylindrical +and concave. A radial magnetic field is create d by the concave poles. +- The armature's ends are joined by two slip rings. They spin in time with +the coil. Metal slip rings that are isolated from one other are used. +- There are two carbon brushes, B1 and B2. Each brush has one end that +is connected to an e xternal circuit and the other end that is in touch with +the rotating slip rings. Brushes are linked to a galvanometer and do not +revolve with the coil in this case. +- A diesel engine, flowing water, steam, or high -speed wind rotate the +axle mechanically from the outside. + +● Working: +- The armature changes its relative orientation with respect to the +magnetic field as it rotates along an axis perpendicular to the field. +- As a result, the flux is constantly altering over time. +- An emf is produced by a shift in magnetic flux.Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +- A diesel engine, flowing water, steam, or high -speed wind rotate the +axle mechanically from the outside. + +● Working: +- The armature changes its relative orientation with respect to the +magnetic field as it rotates along an axis perpendicular to the field. +- As a result, the flux is constantly altering over time. +- An emf is produced by a shift in magnetic flux. +- An electric current passes through the armature if the outer terminals +are linked to an external circuit. +- The galvanometer needle deflection indicates that an emf has been +induced. After every half rotation o f the coil, the direction of the +induced emf is reversed. +- As a result, the current changes direction twice in one coil revolution. +- Take a look at the diagram below to see how the direction of current +changes: + + 16 + + + +- Alternating current is a type of current that alternates its direction at +regular intervals (AC). +- A split -ring type commutator must be utilised to create a direct current +(DC) generator. One brush is always in contact with the arm travelling +up in the fiel d, while the other brush is always in contact with the arm +travelling down. In such a generator, a unidirectional current is +generated. +- The frequency of the AC current produced in India is 50 hertz (Hz). The +coil rotates at a rate of 50 revolutions per sec ond for one second. In one +second, the current changes direction 100 times in 50 rotations. + +● DC Generator: +- The output generated here is one -way. +- To do this, the slip rings are replaced with split rings. +- A split -ring type commutator must be utilised to create a direct current +(DC) generator. One brush is always in contact with the arm travelling +up in the field, while the other brush is always in co ntact with the arm +travelling down. In such a generator, a unidirectional current is +generated. +- alternating current + +● Direct current:Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +- A split -ring type commutator must be utilised to create a direct current +(DC) generator. One brush is always in contact with the arm travelling +up in the field, while the other brush is always in co ntact with the arm +travelling down. In such a generator, a unidirectional current is +generated. +- alternating current + +● Direct current: +DC, occurs when the current flows in the same direction. The current +generated by a cell or battery is one -way. As a result, it's a DC source. In +an electrical circuit, it is represented as: + + + + + 17 + + + +The voltage V/s time graph for a DC source is represented as fo llows: + + + +The +ve and -ve terminals are fixed. + +● Alternating Current: +- Alternating current is defined as a current that changes direction at +regular intervals. +- The majority of power plants produce AC current. +- In an electrical circuit, it is represented as: + + + +The voltage V/s time graph for an AC source is represented as follows: + + 18 + + + + +The current changes direction every half cycle, hence there are no stable +terminals. +● Domestic Electric Circuits: +Electric power is typically generated in locations that are remote from +where it is consumed. Electricity is generated at 11,000 volts at the +generating station. This voltage alternates at a 50 Hz frequency. +To reduce energy loss during transmission, power is transported over long +distances at high voltage. +● Domestic Wiring: +The live wire, neutral wire, and earth wire are the three wires that br ing +electricity into our home. We use a colour code for insulating these wires +to minimise confusion. The live wire is red, whereas the neutral wire is +black. The earth cable is insulated with green plastic. The live wire has a +220 volt potential, while th e neutral wire has no potential. As a result, the +potential difference between the live and neutral wires is 220 volts.Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +electricity into our home. We use a colour code for insulating these wires +to minimise confusion. The live wire is red, whereas the neutral wire is +black. The earth cable is insulated with green plastic. The live wire has a +220 volt potential, while th e neutral wire has no potential. As a result, the +potential difference between the live and neutral wires is 220 volts. + + 19 + + +- The earth wire is constructed of copper and is substantially thicker. It's +connected to a copper plate buried deep underground on one end. The +earth is connected to the electric metre, which is subsequently +connected to the main switch. +- Electricity is deli vered to our homes via a main supply, which is either +supported by above electric poles or underground wires. +- The live and neutral wires from the electric pole enter a box with a +primary fuse F1 installed directly outside our house. The live wire is +linked in series with the fuse. This is because the live wire is the sole +one with a high potential of 220 volts, whereas the neutral wire has no +potential. +- F1 has a high amperage rating of roughly 50 amperes. As a result, it +prevents any damage to the entire electrical wiring entering the house, +such as fire, caused by a short -circuit or overload. +- The two lines then enter the electricity metre, which keeps tr ack of how +much electricity we use in kilowatt -hours (kWh). The electric supply +department of our city erected this metre. +- The two wires that emerge from the metre are then connected to a main +switch in a distribution box. For customer safety, another fuse F2 is +connected in series with the live wire in this box. +- In a house, there are two different circuits: lighting circuit and power +circuit. The lighting circuit, which uses a 5 A fuse, is used to power +electric bulbs, fans, radios, TVs, and tube lights, w hile the power circuit,Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +switch in a distribution box. For customer safety, another fuse F2 is +connected in series with the live wire in this box. +- In a house, there are two different circuits: lighting circuit and power +circuit. The lighting circuit, which uses a 5 A fuse, is used to power +electric bulbs, fans, radios, TVs, and tube lights, w hile the power circuit, +which uses a 15 A fuse, is used to power electric heaters, electric irons, +geysers, and refrigerators, among other things. +- The distribution circuits are always linked together in parallel. Even if +a defect or short -circuiting occurs in one line of a parallel circuit, the +corresponding fuse blows, keeping the other circuits and appliances +intact and preventing damage to the entire house. The power -fuse will +blow if a short -circuit happens in the power circuit, but our lights will +continue to burn because the lighting circuit is untouched. +- All other electrical equipment can use the main line's steady voltage. As +illustrated in the diagram, in addition to the two wires, a third wire +known as the ground wire enters our home. +- The earth is connected to the electric metre first, and then to the main +switch. This cable, together with the live and neutral wires, is then run +into the rooms. + + + + 20 + + +● Electric Fuse: +- The term "electric fuse" refers to a device that limits the current in an +electric circuit. The fuse protects the circuit as well as the electrical +equipment from damage. +- The fuse wire is usually made of a lead and tin alloy. It has a low melting +point and will break the circuit if the current is too high. The maximum +current allowed across the circuit determines the thickness and length +of the fuse wire. +- In the beginning of the electric circuits, it is connected in series. +- The fuse wire becomes heated and melts when the circuit current +exceeds a preset value owing to voltage variations or short -circuiting.Magnetic Effects of Electric Current CBSE class 10 Notes CBSE Science Chapter 13 [PDF].txt +point and will break the circuit if the current is too high. The maximum +current allowed across the circuit determines the thickness and length +of the fuse wire. +- In the beginning of the electric circuits, it is connected in series. +- The fuse wire becomes heated and melts when the circuit current +exceeds a preset value owing to voltage variations or short -circuiting. +As a result, the connection is broken as illustrated in the diagram, and +no current flows. The appliance will not be damaged as a result of this. + +● Causes of Damage to Electric Circuits: +Overloading +- When a significant number of high -power electrical appliances (such as +an electric iron or a water heater) are turned on at the same time, the +circuit draws an enormous amount of current. This is known as +overloading, and it can lead to overheating of the wire and a fire. It can +also occur as a result of an unintentional increase in supply voltage. + +● Short -circuiting: +- When the live and neutral wires of an electric circuit come into direct +touch, a short circuit develops. The wires may come into contact with +each other due to a faulty connection or the insulation wearing away. +This condition causes the wires to overheat, resulting in a fire. + +● Earthing of Electrical Appliances: +- The metal of an electrical equipment is 'earthed' to prevent electric +shocks. The term "earthed" refers to a metal wire (copper) that connects +the appliance's metal case to the earth (at zero potential). The earth wire +has one end that is buried deep in th e ground and the other end that is +attached to the three pin socket. +- The metal casing of the electrical appliance will remain at zero potential +when it is switched on because it is in contact with the earth wire in the +three pin socket. It thereby protects us from receiving an electric shock +even if we unintentionally conta ct it.How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +IntroductionAll living organisms multiply or reproduce and produce offspring of a similar kind. Reproduction is an essential process for the existence of a species and the continuation of life.Here, in this chapter, we will learn about how different unicellular and multicellular organisms such as bacteria, algae, plants, animals and human beings reproduce. What are the different reproductive structures and modes of reproduction such as cell division, vegetative reproduction, asexual reproduction, and sexual reproduction.ReproductionReproduction is the process by which all organisms multiply in number and increase their population.To know more about Reproduction, visit here.Asexual reproductionAsexual reproduction is a method of reproduction that involves only one organism. A single organism reproduces two or multiple organisms on its own. This is seen in all unicellular organisms, some multicellular organisms and a few plants.To know more about Asexual reproduction, visit here.Sexual reproductionThe mode of reproduction that involves two individuals; one male and one female. They produce sex cells or gametes which fuse to form a new organism.To know more about Sexual reproduction, visit here.Asexual ReproductionFission•Fission is an asexual reproduction that is common in most of the unicellular organisms.•When the fission results in two daughter cells, it is binary fission (e.g. paramecium).•When fission results in many daughter cells, it is called multiple fission (e.g. Plasmodium).•Planes of fission may be different for different organisms. + + To know more about Binary Fission, visit here.Budding•Budding is a type of asexual reproduction in which a small cyst-like structure is formed on the parent’s body, which gives rise to a new individual.•Bud may remain attached to the parent (yeast) or may separate and become a new individual (hydra).How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +To know more about Binary Fission, visit here.Budding•Budding is a type of asexual reproduction in which a small cyst-like structure is formed on the parent’s body, which gives rise to a new individual.•Bud may remain attached to the parent (yeast) or may separate and become a new individual (hydra). + +To know more about Budding, visit here.Regeneration and fragmentation•Regeneration is the process of growing back the lost organ or body part by the organism (e.g. lizard).•Fragmentation is the process by which an organism gets fragmented into smaller pieces and each piece grows into a whole new organism.•E.g. Planaria, Hydra + +•Fragmentation and Regeneration in Hydra To know more about Regeneration and fragmentation, visit here.Spore formationOrganisms such as fungi make spores that can grow into complete new individuals when dispersed from their fruiting body. Spores are produced inside sporangia. They are covered by a thick outer layer that protects them in adverse conditions. When spores get suitable environmental conditions they germinate and begin to grow. + +Read more: Spore FormationVegetative propagation + +•This is a type of asexual reproduction seen in plants.•The vegetative part of the plant, like leaves, stem, roots, gives rise to a new plant.•Vegetative propagation can be artificial or natural.•Natural vegetative propagation happens through leaves (e.g. bryophyllum), stem (e.g. turmeric, ginger), runners/stolon (e.g.grass runners, strawberry), bulbs ( e.g. onion, lily), etc.•Artificial methods include cutting, grafting, layering and plant tissue culture.To know more about Vegetative propagation, visit here.Sexual ReproductionTypes of Cell division + +Two types of cell division are seen in eukaryotic organisms:Mitosis•Takes place in somatic cells•Maintains the chromosome number•Produces two, diploid daughter cells•Required for asexual reproduction, development and growth, cell replacement and  regenerationMeiosisHow-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +Two types of cell division are seen in eukaryotic organisms:Mitosis•Takes place in somatic cells•Maintains the chromosome number•Produces two, diploid daughter cells•Required for asexual reproduction, development and growth, cell replacement and  regenerationMeiosis + +•Takes place in sex cells•Reduces the number of chromosomes by half•Produces four haploid daughter cells•Required for sexual reproduction, i.e gamete formationTo know more about Cell division, visit here.The Reproductive SystemIn humans, there is a remarkable difference in the male and female reproductive systems. Testes are the main reproductive structure in males where sperms (male gametes) are produced and ovum (female gamete) is produced inside the ovary. Let us now learn in detail about male and female reproductive systems in humans.To know more about Human Reproductive System, visit here.Male reproductive system•The main reproductive organ in males is a pair of testes.•They produce the male sex cells called sperms and also produce the male sex hormone testosterone.  + +Male main reproductive organs•The main reproductive organ in males is a pair of testes.•They are present in scrotal sacs outside the body and contain seminiferous tubules as the structural and functional unit.•Male sex cells, sperms, are produced by seminiferous tubules and mature in the epididymis.•Leydig cells or interstitial cells present in between the seminiferous tubules secrete hormone testosterone.Male accessory reproductive organs•Several accessory reproductive organs aid in the reproductive process.•The prostate gland and the seminal vesicles are glands of the reproductive system which make semen and nourish the sperm.•Penis, having urethra passing through it, is called copulatory organ.Male Ducts•In males, the vas deferens and the urethra are the main ducts.•A single vas deferens carries sperms from respective testis up to the urethra.How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +•The urethra acts as a common passage for semen and urine.To know more about Male Reproductive System, visit here.Female reproductive systemThe human female reproductive system consists of a pair of ovaries, a pair of fallopian tubes/oviducts and the accessory organs such as the uterus and the vagina.  +Female main reproductive organ + +•The main reproductive organ in a female is a pair of ovaries.•They produce the female sex cells called eggs or ova and also produce female sex hormones called estrogen and progesterone.Female accessory reproductive organ•Uterus, oviducts, and vagina are the accessory reproductive organs in human females.•The uterus is the site of fetal development and the vagina receives sperm from the male. Ovum is carried from ovaries to the uterus through a pair of oviducts.To know more about the Female reproductive system, visit here.Menstrual CycleMenstruation•Menstruation is the cyclic event of the release of the ovum from the ovary and its removal from the body when fertilization does not happen.•During menstruation, the blood-rich endometrium of the uterus also breaks down while the ovum is removed from the body.•Two pituitary hormones, LH and FSH, and two ovarian hormones, estrogen and progesterone, all have their roles in menstruation.•In humans, the cycle repeats every 28 days.To know more about Menstrual Cycle, visit here.FertilizationHuman reproductionHumans reproduce sexually. The male produces sperms and the female produces eggs. When the sperm fuses with the egg, it forms a zygote that gives rise to a new progeny.To know more about Fertilization, visit here.Contraceptive Methods + +Reproductive healthReproductive health deals with the prevention of STDs and unwanted pregnancy. Understanding the reproductive system is also a part of reproductive health awareness.Contraceptives•Contraceptives are devices that prevent unwanted pregnancy and help avoid STDs.How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +Reproductive healthReproductive health deals with the prevention of STDs and unwanted pregnancy. Understanding the reproductive system is also a part of reproductive health awareness.Contraceptives•Contraceptives are devices that prevent unwanted pregnancy and help avoid STDs. + +•Contraceptives can be of various types such as mechanical barriers, hormonal/chemical methods, surgical methods, etc.Coitus Interruptus•It is a very unreliable contraceptive method where the coitus is stopped before the male ejaculates inside the female reproductive tracts.Rhythm Method•Another unreliable method of contraception is where coitus is avoided when the female is fertile and the chances of fertilization are very high.Condoms•One of the most effective methods of contraception.•A mechanical barrier that stops the semen from entering the female tract preventing pregnancy.•It also avoids the possibility of contracting STDs.Diaphragms•Diaphragms are barriers that can be added inside the female reproductive tracts.•They stop the entry of semen inside the female tract and thus prevent pregnancy.Contraceptive Pills•Contraceptive pills are chemical methods of contraception.•They change the level of hormones in the body that prevents the release of the ovum from the ovaries.Emergency Pill•Emergency pills are those pills which can be taken after coitus to avoid pregnancy.•They quickly change the level of hormones in the body and prevent a successful implantation even if the egg gets fertilized.IUD•IUD stands for Intrauterine Device.•They can be used for a couple of years.•It is a device that is inserted into the uterus, changing its shape and preventing successful implantation of the zygote.Sterilization•Sterilization is a surgical method of going permanently sterile.•This can be done in both males and females.•In males, it is called vasectomy and in females, it is called tubal ligation.To know more about Contraceptive Methods, visit here.How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +Reproduction in PlantsPlants reproduce by both, asexual and sexual methods. Vegetative propagation is a type of asexual reproduction in plants. Let’s learn now about sexual reproduction in plants.To know more about Reproduction in Plants, visit here.Sexual reproduction in flowering plants•Sexual reproduction in plants happens through flowers.•Essential whorls of the flowers such as androecium and gynoecium help in the sexual reproduction of plants.Read more:  Sexual Reproduction in PlantsNon-essential parts of flowers•The typical structure of flowers contains essential whorls and non-essential whorls.•Sepals and Petals are called non-essential whorls as they do not directly take part in reproduction.•Sepals protect the inner delicate whorl during bud condition and also perform photosynthesis if they are green in colour.•Petals, when they are coloured, attract insects for pollination.Essential whorls of flowers•Androecium and gynoecium are called as essential/reproductive whorls of a flower.•Androecium produces pollen grains containing male gametes and gynoecium produces ovules which are female gametes.•Bisexual flowers contain both the whorls while unisexual flowers contain either of them.•Each individual member of androecium is called a stamen and consists of anther and filament.•Anther produces haploid pollen grains. + +•Each individual member of gynoecium is called pistil and consists of stigma, style and ovary.How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +•Each individual member of gynoecium is called pistil and consists of stigma, style and ovary. +PollinationThe process of transfer of pollen grains from anthers to the stigma of a flower is known as pollination.•It is required for fertilization.•Pollination has two types, self-pollination (autogamy) and cross-pollination (allogamy).•In self-pollination, the transfer of pollen grains takes place from anthers to the stigma of the same flower or another flower of the same plant.•In cross-pollination, pollens are transferred from anthers to the stigma of another flower.•Many pollinating agents play their roles in cross-pollination. Examples: water, wind, insects, birds, bats, etc.Know more: PollinationFertilizationFusion of male and female gametes is known as fertilization.•In flowering plants after pollination, the pollens germinate on the stigma surface of pistil and generate two male nuclei. + +•Ovule has egg cell and two polar nuclei.•One male nucleus fuses with two polar nuclei and forms triploid endosperm.•Another male nucleus fuses with the egg cell and forms the zygote that gives rise to the embryo and future plant.•After fertilization, ovary becomes fruit and ovules turn into seeds. All other parts wither away. +Know more: Fertilisation in PlantsAlso Check:•CBSE Class 10 Science Chapter 7 Control and Coordination Notes•CBSE Class 10 Science Chapter 9 Heredity And Evolution Notes•NCERT Solutions for Class 10 Science Chapter 8: How do Organisms Reproduce?•NCERT Exemplar Class 10 Science Solutions for Chapter 8 - How Do Organisms Reproduce•Real Numbers Class 10 Notes: Chapter 1Frequently Asked Questions on CBSE Class 10 Science Notes Chapter 8: How do Organisms ReproduceWhat is difference between fission and fusion?How-do-Organisms-Reproduce-CBSE class-10-Notes Chapter 8.txt +Fission is the process where an atom splits into two or more smaller parts. Whereas fusion involves the fusing of two or smaller atoms into a larger particular.What is fragmentation?Fragmentation is a form of asexual reproduction where the parent organism breaks into fragments. Each of these fragments are capable of growing independently into a new organism.What is a gamete cell?Gamete cell are the reproductive cells of an organism. Female gametes are referred to a ova or egg cells and male gametes are known as sperms.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +IntroductionHeredity refers to the passing of characteristics from one generation to the next. Evolution is defined as the gradual process by which a simple life form leads to the development of complex organisms over a period of time, spanning several generations.Here in this chapter, we will learn about the mechanism by which variations are created, the rules of heredity determining their pattern of inheritance, and how the accumulation of these variations leads to evolution.HeredityThe transfer of traits from one generation to the next is termed heredity. Genes are the functional units of heredity, that transfer characteristics from parents to offspring. Genes are short stretches of DNA that code for a specific protein or RNA. Genetics is the branch of biology that deals with the study of genes, heredity and variations.Sexual reproduction•The mode of reproduction involves two individuals; one male and one female.•They produce sex cells or gametes which fuse to form a new organism.Genes•Gene is the functional unit of heredity.•Every gene controls one or several particular characteristic features in living organisms.Read more: GenesHeredityThe process by which the features of an organism are passed on from one generation to another is called heredity.•The process is done by genes, which define the characters in the organism.To know more about Heredity, visit here.Mendel's work•Gregor Johann Mendel, known as 'Father of Genetics', was an Austrian Monk who worked on pea plants to understand the concept of heredity.•His work laid the foundation of modern genetics. + +•He made three basic laws of inheritance - The Law of Dominance, The Law of Segregation and The Law of Independent Assortment.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +•He made three basic laws of inheritance - The Law of Dominance, The Law of Segregation and The Law of Independent Assortment. +Dominant traitsThe traits that express themselves in an organism in every possible combination and can be seen are called Dominant traits.•In Mendel’s experiment, we see that the tall trait in pea plants tends to express more than the short trait.•Therefore, the tall trait of the plant is said to be dominant over the short trait.Recessive traitsA trait which is not expressed in the presence of a dominant allele is known as recessive.•So, recessive character/trait is present in an organism but cannot be seen if a dominant allele exists.To know the difference between Dominant traits and Recessive traits, visit here.Monohybrid cross•When only one character is considered while crossing two organisms, then such a cross is known as a monohybrid cross. + +•The ratio of characters, arising out of this cross, at F2 generation is called the monohybrid ratio.•E.g., If a tall plant (TT) is crossed with a dwarf plant (tt), we get 3 tall:1 short plant at the end of the F2 generation.•So, 3:1 is a monohybrid ratio.•Here, the height of the plant is considered at a time.Below is the example of a monohybrid cross between a true-breeding pea plant with green pods (GG) and yellow pods (gg). Here, the green colour of the pod is the dominant trait. Hence, in the F1 generation, all plants contain green pea pods. +To know more about Monohybrid cross, visit here.Dihybrid cross•When two characters are considered while crossing two organisms, then such a cross is known as a dihybrid cross.•The ratio of characters, arising out of this cross, at F2 generation is called the dihybrid ratio.•E.g., If a plant with round and green pea is crossed with a plant with wrinkled and yellow pea,•The first generation plants would all have round and green peas.•On crossing the same for an F2 generation, we would observe four combinations of characters in the ratio of 9:3:3:1.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +•Thus, 9:3:3:1 is the dihybrid ratio. +To know more about Dihybrid cross, visit here.InheritanceIn Biology, inheritance pertains to the transfer of traits from one generation to another.To know more about Mendel's laws of inheritance, visit here.Laws of Mendel + +Law of Dominance says that a gene has two contrasting alleles and one always expresses itself in the organism.It is called the dominant gene and it expresses in any possible combination.Law of Segregation says that traits get segregated completely during the formation of gametes without any mixing of alleles.Law of Independent Assortment says that the traits can segregate independently of different characters during gamete formation.Sex determination•The process of determining the sex of an individual, based on the composition of the genetic material is called sex determination.•In different animals, sex of an embryo is determined by different factors.•In humans, sex determination happens on the basis of the presence or absence of Y chromosome.•XX is female and XY is male•An ovum always contains X chromosome.•An ovum, upon fusion with Y containing sperm, gives rise to a male child and upon fusion with X containing sperm gives rise to a girl child.To know more about Sex determination, visit here.TraitsTraits are characteristic features of an organism, manifested in a physical form that is visible or in a physiological aspect of the organism.Acquired characters•The traits that are acquired by an organism over the period of its lifetime are termed acquired characteristics.•These characters that are not passed on to the DNA of germ cells do not get transferred to the next generation. E.g. loss of muscles and less weight due to starvation, loss of limb or tails due to injury, etc.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +Inherited characters•The traits that are inherited from the parents are called inherited characters.•These traits always get transferred to the next generation but depending on the dominance or recessiveness they may or may not be expressed.•Examples are height, skin colour and eye colour.To know more about Acquired and Inherited Traits, visit here.VariationVariation is the measure of the difference between individuals of the same species. Offspring is not identical to parents, there exist some variations. Each individual in a population differs from the others. Recombination and mutation are the main causes of variations.Sexually reproducing organisms show great variation among individuals of a species and the long-term accumulation of variations plays a significant role in evolution. The selection of variants by environmental factors is one of the driving factors of evolutionary processes.Genetic variationsThe differences in the DNA sequences among every organism leading to the diverse gene pool are called genetic variations. These differences lead to different/varied physical characters or biochemical pathways.To know more about Genetics, visit here.Natural selection•It is the phenomenon by which a favourable trait in a population of a species is selected.•Changing natural conditions exert equal pressure on all the existing species.•The species/organisms which are better adapted to the changing conditions survive and reproduce i.e. selected by nature and species/organisms which cannot adapt perish i.e. rejected by nature.SpeciationGenetic driftNatural selection can play an important role in deciding the traits that survive in a population. However, random fluctuations in gene variants are seen on many occasions. This phenomenon is known as genetic drift. Thus, genetic drift is a change in the frequency of an existing allele in a small population.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +Genetic drift may cause a gene variant to disappear from the population and thus reduce genetic variation.SpeciationIt is the process of formation of a new species from existing ones due to several evolutionary forces like genetic drift, isolation of populations, natural selection, etc.  Speciation leads to diversity in the ecosystem and the diversity and diversity lead to evolution.To know more about Speciation and evolution, visit here.Gene flowGene flow is the transfer of genes from one population to the next. This occurs due to migration or the introduction of organisms to a new population. This results in the change in gene frequencies of a population.PopulationA population is a community or a group of animals, plants or any living organism that can reproduce with each other and have fertile, viable offspring.Charles Darwin•Charles Darwin also called the "Father of Evolution" was an English Naturalist and Biologist.•Five years of the expedition in a ship called HMS Beagle to Galapagos Island helped him write his theory of evolution.•In 1859 he published a book called Origin of Species, in which he put his theory of evolution in detail.To know more about Charles Darwin's Contribution to the Theory of Evolution, visit here.Evolution and FossilsEvolutionEvolution is a tangible change in the heritable characteristics of a population over several generations. These changes can give rise to a new species or the species might change themselves to become better adapted to the surrounding environment.Read more: EvolutionHeredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +Origin of species•After a successful expedition on HMS Beagle, Charles Darwin wrote a book on what he observed on the Galapagos Islands.•In the book named 'The Origin of Species, he wrote a detailed theory of evolution which was mostly based on Natural Selection.Origin of life - Haldane's theory•JBS Haldane was a British Scientist who theorized that life originated from organic and lifeless matter.•His theory was proved to be correct by Urey and Miller’s experiment.•It was called the theory of abiogenesis.Evolutionary evidence - fossils•There are plenty of pieces of evidence to support the theory of evolution.•Fossils happen to be the biggest of them.•Fossils are the preserved remains of ancient animals or plants that died millions of years ago.•The fossils help us understand the anatomy and even physiology of these organisms and understand how evolution worked and led to the formation of organisms that we see today.Formation of FossilsFossils are important pieces of evolutionary evidence and are formed by the following steps:•Organisms die and they get buried in mud and silt.•The soft tissues of the body get quickly leaving behind the hard bones or shells•Over time sediments build over it and harden into rock•As the bones decay, mineral seep in to replace the contents cell by cell, process called as petrification•If bones decay completely, it leaves behind the cast of the animal.To know more about Fossils, visit here.Evolutionary relationshipsEvolutionary relationships of animals can be deduced by studying the homologous organs and analogous organs.Homologous organs are those which have a similar structure but different function.•Wings of birds and forelimbs of mammals: they have similar structure but are modified to suit different functions•A tendril of pea plant and spine of barberry plant: both are modified leaves, but perform different functions.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +Analogous organs are those which have a similar function but a different structure and origin too.•Wings of bats, birds and wings of insects: both are used for flying, but structurally are very different•Leaves of opuntia and peepal: both perform photosynthesis, but leaves of Opuntia are modified stem whereas peepal leaves are normal leaves. +To know more about Fossils Evolutionary Relationships, visit here.Evolution by stage•Evolution is a slow process and does not happen overnight.•There are several stages in the evolution of almost every animal that we see today.•Complexities do not evolve suddenly, but evolve bit by bit and may have limited use at certain stages.•This gradual evolutionary process is called evolution by stages.To know more about Evolution by Stages, visit here.Artificial selection•Sometimes a single species can evolve into several different species due to artificial selection. + +•E.g. the cabbage family. A single ancestor in the cabbage family gave rise to several different species due to the selection of different traits.Molecular phylogeny•The evolutionary relationship among different biological species is called phylogeny.•It gives rise to an evolutionary tree.•In molecular phylogeny these relationships are studied at the hereditary molecular level, mainly using DNA sequences.•It involves the analysis of DNA composition and gene comparison between different species.Human Evolution•Humans are known to belong to the primate family.•Humans today have a very close genetic connection to chimps and other primates.•While the complete evolutionary process of Humans from Primates is still a mystery, a larger picture of human evolution has been formed.•Some of the ancestors of Humans include Dryopithecus, Ramapithecus, Australopithecus, Homo erectus, Homo sapiens neanderthalensis, Cro-magnon man, and finally us, the Homo sapiens.•Human evolution traces back to Africa. Then they migrated all over the world.Heredity-and-Evolution-CBSE class-10-Notes Chapter 9.txt +Migration of Early HumansTo know more about Human Evolution, visit here.Also Check:•CBSE Class 10 Science Chapter 8 How Do Organisms Reproduce Notes•NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution•NCERT Exemplar Class 10 Science Solutions for Chapter 9 - Heredity And EvolutionFrequently Asked Questions on CBSE Class 10 Science Notes Chapter 9: Heredity and EvolutionWhat is evolution? + +The development of plants, animals, etc over many thousand years from simple forms to complex advanced forms.What does the Law of Segregation state?The law of segregation states that each individual that is a diploid has a pair of alleles (copies) for a particular trait.What is meant by natural selection?The process through which organisms adapt and change themselves in huge populations is known as natural selection.CBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +IntroductionThe human body is a complex machine performing tons of functions and processes to maintain and sustain life. Explore how the body controls its movements and coordinates its actions with other parts of the body and the environment by exploring notes for Class 10 Chapter 7 Control and Coordination.The Nervous SystemMovement in organismsThe ability of organisms to move certain body parts is movement.When they move from one place to another, it is called locomotion.Organisms show movements in response to stimuli.Introduction to control & coordination•Organisms move in response to various kinds of stimuli like light, heat, nutrients/food, etc.•All the activities in animals are controlled and coordinated by the nervous and endocrine systems.•Hormones are chemical messengers, which assist the nervous system in carrying out various functions. They are secreted by endocrine glands.•Hormones in plants coordinate the movements.To know more about The Nervous System, visit here.THE NERVOUS SYSTEM + +NeuronNeuron is the structural and functional unit of the nervous system.•Each neuron has three main parts: dendrites, cyton/soma/cell body and axon.•Dendrites receive impulses from other neurons.•Cyton/soma processes the impulse.•Axon transmits the impulse, either to another neuron or to muscles/glands, etc.•Axon may be myelinated or non-myelinated.•The impulse transmission is faster in myelinated neurons.CBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +Central nervous systemThe central nervous system (CNS) is made up of the brain and the spinal cord. Functions of different parts of the brain are:•The cerebrum is responsible for reasoning, logic, emotions, speech, memory, visual processing, recognition of auditory and taste stimuli, etc.•Cerebellum regulates and coordinates body movements, posture and balance.•Pons relays signals from the hindbrain to the forebrain.•Medulla Oblongata controls all involuntary movements like vomiting, sneezing, yawning, heartbeat, breathing, blood pressure, etc.•Medulla oblongata continues as the spinal cord which runs through the vertebral column and it controls reflex actions. + +Read more: Central Nervous SystemPeripheral nervous system•The nerves coming out from the brain and the spinal cord constitute the peripheral nervous system (PNS).•There are 12 cranial nerves and 31 spinal nerves in humans.Read more: Peripheral Nervous SystemSomatic nervous system•It forms a part of the PNS.•The nerves of PNS that control the voluntary actions of the body form the somatic nervous system.Autonomic nervous system•All the nerves of the PNS that control the involuntary actions in the body form the autonomic nervous system. E.g. respiration, heart rate, blood pressure, digestion, etc. are regulated by the autonomic nervous system.CBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +•Two divisions of the autonomic nervous system are the sympathetic and parasympathetic nervous system.•The sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response, while the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high-energy functions.Reflex actionReflex action is a sudden, involuntary reaction of the body in response to stimuli.To know more about Reflex Action, visit here.Reflex arc•It is the path followed by an electrical impulse during a reflex action.•The impulse travels from the receptor organ to the spinal cord/brain. It is processed there and the information is brought back to the concerned muscle to carry out the action.•Thus, the receptor organ, sensory/afferent neuron, interneuron, motor/efferent neuron and effector organ are the components of a reflex arc. + +Protection of CNSThe brain is protected by 3 main layers -•The bony skull (cranium)•The cerebrospinal fluid•The meninges (Dura mater, Arachnoid and Pia mater).Plant Hormones and MovementsPlant hormonesControl and coordination in plants are carried out by hormones. + +To know more about Plant hormones, visit here.Growth independent movementsThe movements which are not growth related are called nastic movements. These movements occur in response to environmental stimuli but the direction of response is not dependent on the direction of the stimulus.•The movement in the touch-me-not plant is thigmonastic movement (movement in response to touch).Plant HormoneFunctionAuxinHelps in Growth of Plant TissueCytokininPromotes Cell division, delays ageing of cellsGibberellinsHelps in the growth of stems, initiates seed germination, promotes flowering, cell division and seed growth after germinationAbscisic acidInhibits growth and causes wilting of leaves, promotes dormancy of buds and seedsEthyleneThis is a gaseous hormone which causes the ripening of fruitsCBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +Growth-related movements in plantsThe movements which are growth related are called tropic movements. These movements occur in response to environmental stimuli and the direction of the response is dependent on the direction of the stimulus.To know more about Tropic Movements in Plants, visit here.Examples:•Phototropic movement (light-dependent)•Geotropic movement (gravity-dependent)•Chemotropic movement (chemical-dependent)•Hydrotropic movement (water-dependent)•Thigmotropic movement (touch dependent)GeotropismMovement of plant parts in response to earth's gravitational force is known as geotropism/gravitropism.•Towards gravity - positive geotropism•Away from gravity - negative geotropism•The root grows towards gravity and shoot grows away from gravity +  + +PhototropismMovement of plant parts in response to light is known as phototropism.•Towards light-positive phototropism•Away from light - negative phototropism•Stems move towards light and roots move away from lightTo know more about Phototropism, visit here.HydrotropismMovement of plant parts in response to water or moisture.•Towards water-positive hydrotropism•Away from water - negative hydrotropism•Again, root movement in search of water is positive hydrotropism•E.g. movement of roots towards high humidity level +ChemotropismMovement of plant parts in response to chemical stimuli is known as chemotropism.•Towards chemical - positive chemotropism•Away from chemical - negative chemotropism•The growth of pollen tube towards the ovule is positive chemotropism + +ThigmotropismMovement of plant parts in response to touch is called as thigmotropism.•Towards touch - Positive thigmotropism•Away from touch - negative thigmotropism•Movement of tendrils around the support is positive thigmotropismCBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +ThigmotropismMovement of plant parts in response to touch is called as thigmotropism.•Towards touch - Positive thigmotropism•Away from touch - negative thigmotropism•Movement of tendrils around the support is positive thigmotropism +The Endocrine SystemExocrine glandsExocrine glands are glands that discharge secretions by means of  ducts, which open onto an epithelial surface. Endocrine glandsEndocrine glands are the ductless glands which secrete hormones into the bloodstream in humans.The endocrine glands present in the human body are the pituitary, thyroid, adrenal, pineal, pancreas, ovary (female), testis (male), etc. Let us now learn more about each of the glands below. + +To know more about Exocrine glands, visit here.Pituitary gland•It is a pea-sized gland located at the base of the brain.•It is the master gland as it controls the secretions of all the other endocrine glands.•It also secretes Growth Hormone (GH). Under-secretion of GH causes Dwarfism and over-secretion causes Gigantism in children and ‘Acromegaly’ in adults.To know more about Pituitary gland, visit here.Thyroid gland•It is a butterfly-shaped gland located in the throat.•It secretes the hormone ‘Thyroxine’ which regulates the metabolism of the body.•Iodine is required to synthesize thyroxine in the body.•In the case of iodine deficiency, under-secretion of thyroxine leads to goitre.To know more about Thyroid gland, visit here.CBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +Pancreas•It is a leaf-like gland present behind the stomach in the abdomen.•It is an endocrine as well an exocrine gland.•As an endocrine gland, it manufactures two hormones - Insulin and glucagon. Both these hormones act antagonistically and regulate the sugar level in the blood.•As an exocrine gland, it secretes enzymes to break down the proteins, lipids, carbohydrates and nucleic acids in food.•An insufficient amount of insulin from the pancreas leads to diabetes.To know more about Pancreas, visit here.Adrenal gland•Occurs in pairs above each kidney.•It decreases in size with age.•Secrets the hormone adrenaline which helps in flight and fight response.•Also secretes nor adrenalineTo know more about the Adrenal gland, visit here.Gonads•Gonads are the gamete-producing organs - testes in males and ovaries in females.•The testes produce the male hormone testosterone and the ovaries produce the female hormones oestrogen and progesterone.•Testosterone and oestrogen help in producing gametes and are responsible for the sexual characteristics of males and females respectively.•Progesterone is the pregnancy hormone.To know more about Gonads, visit here.Other endocrine organs•The other endocrine organs include the hypothalamus, parathyroid, pineal and thymus glands.To know more about The Endocrine System, visit here.Also Check:•CBSE Class 10 Science Notes Chapter 6 Life Processes•CBSE Class 10 Science Chapter 8 How Do Organisms Reproduce Notes•NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination•NCERT Exemplar Class 10 Science Solutions for Chapter 7 - Control And Coordination•Real Numbers Class 10 Notes: Chapter 1•CBSE Class 10 History Notes Chapter 1 - The Rise of Nationalism in EuropeCBSE-CBSE class-10-Science-Notes-for-Chapter-7-Control-and-Coordination.txt +Frequently Asked Questions on CBSE Class 10 Science Notes Chapter 7: Control and CoordinationWhat is the function of the Central nervous system?The central nervous system (CNS) controls most functions of the body and mind. It consists of two parts: the brain and the spinal cord. The brain is the centre of our thoughts, the interpreter of our external environment, and the origin of control over body movement.What are some facts about the human brain?1. 60% of the human brain is composed of fat2. The brain contains about 100 billion neurons and 100 trillion connections3. The texture of the brain is similar to that of firm jellyHow many parts does the human eye have?The human eye totally consists of 7 parts that work together.cbse-CBSE class-10-science-notes-chapter-4-carbon-and-its-compounds.txt +Carbon and Its Compounds +Soaps and Detergents:- +Cleansing Action of Soap +When soap is added to water, the soap molecules uniquely orient themselves to form +spherical shape micelles. +The non-polar hydrophobic part or tail of the soap molecules attracts the dirt or oil part of +the fabric, while the polar hydrophilic part or head, (−COO−Na+, remains attracted to water +molecules. +The agitation or scrubbing of the fabric helps the micelles to carry the oil or dirt particles +and detach them from the fibres of the fabric.Hard Water +Hard water contains salts of calcium and magnesium, principally as bicarbonates, chlorides, +and sulphates. When soap is added to hard water, calcium and magnesium ions of hard +water react with soap forming insoluble curdy white precipitates of calcium and magnesium +salts of fatty acids. +2C17H35COONa +MgCl 2→ (C17H35COO )2Mg+ 2NaCl +2C17H35COONa +CaCl 2→ (C17H35COO )2Ca+ 2NaCl +These precipitates stick to the fabric being washed and hence, interfere with the cleaning +ability of the soap. Therefore, a lot of soap is wasted if water is hard. +Covalent Bonds +Difficulty of Carbon to Form a Stable Ion +To achieve the electronic configuration of nearest noble gas, He, if the carbon atom loses +four of its valence electrons, a huge amount of energy is involved. C4+ ion hence formed will +be highly unstable due to the presence of six protons and two electrons. +If the carbon atom gains four electrons to achieve the nearest electronic configuration of +the noble gas, Ne, C4− ion will be formed. But again, a huge amount of energy is required. +Moreover, in C4+ ion it is difficult for 6 protons to hold 10 electrons. Hence, to satisfy its +tetravalency, carbon shares all four of its valence electrons and forms covalent bonds. +Ionic BondIonic bonding involves the transfer of valence electron/s, primarily between a metal and a +nonmetal. The electrostatic attractions between the oppositely charged ions hold the +compound together. +Ionic compounds:cbse-CBSE class-10-science-notes-chapter-4-carbon-and-its-compounds.txt +tetravalency, carbon shares all four of its valence electrons and forms covalent bonds. +Ionic BondIonic bonding involves the transfer of valence electron/s, primarily between a metal and a +nonmetal. The electrostatic attractions between the oppositely charged ions hold the +compound together. +Ionic compounds: +1. Are usually crystalline solids (made of ions) +2. Have high melting and boiling points +3. Conduct electricity when melted +4. Are mostly soluble in water and polar solvents +Covalent Bond +A covalent bond is formed when pairs of electrons are shared between two atoms. It is +primarily formed between two same nonmetallic atoms or between nonmetallic atoms with +similar electronegativity. +Lewis Dot Structure +Lewis structures are also known as Lewis dot structures or electron dot structures. +These are basically diagrams with the element's symbol in the centre. The dots around it +represent the valence electrons of the element.  +Lewis structures of elements with atomic number 5-8 +Covalent Bonding in H2, N2 and O2 +Formation of a single bond in a hydrogen molecule: +Each hydrogen atom has a single electron in the valence shell. It requires one more to +acquire nearest noble gas configuration (He). +Therefore, both the atoms share one electron each and form a single bond.Formation of a double bond in an oxygen molecule: +Each oxygen atom has six electrons in the valence shell (2, 6). It requires two electrons to +acquire nearest noble gas configuration (Ne). +Therefore, both the atoms share two electrons each and form a double bond. +Formation of a triple bond in a nitrogen molecule: +Each nitrogen atom has five electrons in the valence shell (2, 5). It requires three electrons +to acquire nearest noble gas configuration (Ne). +Therefore, both atoms share three electrons each and form a triple bond. +Single, Double and Triple Bonds and Their Strengths +A single bond is formed between two atoms when two electrons are shared between them, +i.e., one electron from each participating atom.cbse-CBSE class-10-science-notes-chapter-4-carbon-and-its-compounds.txt +to acquire nearest noble gas configuration (Ne). +Therefore, both atoms share three electrons each and form a triple bond. +Single, Double and Triple Bonds and Their Strengths +A single bond is formed between two atoms when two electrons are shared between them, +i.e., one electron from each participating atom. +It is depicted by a single line between the two atoms. +A double bond is formed between two atoms when four electrons are shared between them, +i.e., one pair of electrons from each participating atom. It is depicted by double lines +between the two atoms. +A triple bond is formed between two atoms when six electrons are shared between them, +i.e., two pairs of electrons from each participating atom. It is depicted by triple lines +between the two atoms.Bond strength: +- The bond strength of a bond is determined by the amount of energy required to break a +bond. +- The order of bond strengths when it comes to multiple bonds is: Triple bond>double +bond>single bond +- This is to signify that the energy required to break three bonds is higher than that for two +bonds or a single bond.Bond length: +- Bond length is determined by the distance between nuclei of the two atoms in a bond. +- The order of bond length for multiple bonds is: Triple bond