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The desire to understand how and why things happen is shared by all branches of what? | government | population | society | science | Scientists may focus on very different aspects of the natural world. For example, some scientists focus on the world of tiny objects, such as atoms and molecules. Other scientists devote their attention to huge objects, such as the sun and other stars. But all scientists have at least one thing in common. They want to understand how and why things happen. Achieving this understanding is the goal of science. |
The scientific revolution took place where starting in the 1500s? | north america | africa | south america | europe | People have probably wondered about the natural world for as long as there have been people. So it’s no surprise that science has roots that go back thousands of years. Some of the earliest contributions to science were made by Greek philosophers more than two thousand years ago. It wasn’t until many centuries later, however, that the scientific method and experimentation were introduced. The dawn of modern science occurred even more recently. It is generally traced back to the scientific revolution, which took place in Europe starting in the 1500s. |
Ionic bonds are electrostatic attractions between two oppositely charged what? | compounds | molecules | gasses | ions | Ionic bonds are electrostatic attractions between two oppositely charged ions. Ions can be formed and then bonded when metal atoms donate their valence electrons to nonmetal atoms. |
What is the theoretical event that began the universe often called? | string theory | Coreolis effect | dark matter | big bang | The generation of an isolated but open system, which we might call a protocell, was a critical step in the origin of life. Such an isolated system has important properties that are likely to have facilitated the further development of life. For example, because of the membrane boundary, changes that occur within one such structure will not be shared with neighboring systems. Rather, they accumulated in, and favor the survival of, one system over its neighbors. Such systems can also reproduce in a crude way by fragmentation. If changes within one such system improved its stability, its ability to accumulate resources, or its ability to survive and reproduce, that system, and its progeny, would be likely to become more common. As these changes accumulate and are passed from parent to offspring, the organisms will inevitably evolve, as we will see in detail in the next chapter. As in living systems today, the earliest steps in the formation of the first organisms required a source of energy to maintain the non-equilibrium living system. There are really two choices for the source of this energy, either light (electromagnetic radiation from the sun) or thermodynamically unstable chemicals present in the environment. There have been a number of plausible scenarios, based on various observations, for the steps leading to life. For example, a recent study based on the analysis of the genes (and the proteins that they encode) found in modern organisms, suggests that the last universal common ancestor (LUCA) arose in association with hydrothermal vents.60 But whether this reflects LUCA or an ancestor of LUCA that became adapted to living is association with hydrothermal vents is difficult (and perhaps impossible) to resolve unambiguously, particularly since LUCA lived ~3.4-3.8 billion years ago and cannot be studied directly. Mapping the history of life on earth Assuming, as seems likely, that life arose spontaneously, we can now look at what we know about the fossil record to better understand the diversification of life and life’s impact on the Earth. This is probably best done by starting with what we know about where the Universe and Earth came from. The current scientific model for the origin of the universe is known as the “Big Bang” (also known as the “primeval atom” or the “cosmic egg”), an idea originally proposed by the priest, physicist and astronomer Georges Lemaître (1894-1966).61 The Big Bang model arose from efforts to answer the question of whether the fuzzy nebulae identified by astronomers were located within or outside of our galaxy. This required some way to determine how far these nebulae were from Earth. Edwin Hubble (1889-1953) and his co-workers were the first to realize that nebulae were in fact galaxies in their own right, each very much like our own Milky Way and each is composed of many billions of stars. This was a surprising result. It made Earth, sitting on the edge of one (the Milky Way) among many, many galaxies seem less important – a change in cosmological perspective similar to that associated with the idea that the Sun, rather than Earth, was the center of the solar system (and the Universe). To measure the movement of galaxies with respect to Earth, Hubble and colleagues combined to types of observations. The first of these allowed them to estimate the distance from the Earth to. |
In the cardiovascular system, net filtration pressure represents the interaction of osmotic pressures and what other pressures? | hydrophilic | uptake | homeostatic | hydrostatic | Interaction of Hydrostatic and Osmotic Pressures The normal unit used to express pressures within the cardiovascular system is millimeters of mercury (mm Hg). When blood leaving an arteriole first enters a capillary bed, the CHP is quite high—about 35 mm Hg. Gradually, this initial CHP declines as the blood moves through the capillary so that by the time the blood has reached the venous end, the CHP has dropped to approximately 18 mm Hg. In comparison, the plasma proteins remain suspended in the blood, so the BCOP remains fairly constant at about 25 mm Hg throughout the length of the capillary and considerably below the osmotic pressure in the interstitial fluid. The net filtration pressure (NFP) represents the interaction of the hydrostatic and osmotic pressures, driving fluid out of the capillary. It is equal to the difference between the CHP and the BCOP. Since filtration is, by definition, the movement of fluid out of the capillary, when reabsorption is occurring, the NFP is a negative number. NFP changes at different points in a capillary bed (Figure 20.16). Close to the arterial end of the capillary, it is approximately 10 mm Hg, because the CHP of 35 mm Hg minus the BCOP of 25 mm Hg equals 10 mm Hg. Recall that the hydrostatic and osmotic pressures of the interstitial fluid are essentially negligible. Thus, the NFP of 10 mm Hg drives a net movement of fluid out of the capillary at the arterial end. At approximately the middle of the capillary, the CHP is about the same as the BCOP of 25 mm Hg, so the NFP drops to zero. At this point, there is no net change of volume: Fluid moves out of the capillary at the same rate as it moves into the capillary. Near the venous end of the capillary, the CHP has dwindled to about 18 mm Hg due to loss of fluid. Because the BCOP remains steady at 25 mm Hg, water is drawn into the capillary, that is, reabsorption occurs. Another way of expressing this is to say that at the venous end of the capillary, there is an NFP of −7 mm Hg. |
What attracts the earth to the sun? | the moon | weight | light | gravity | The earth is attracted to the sun by the force of gravity. Why doesn’t the earth fall into the sun?. |
Fermat’s principle states that light will always take the path of least amount of? | resistance | energy | momentum | time | Fermat’s Principle states that light will always take the path of least amount of time (not distance). This principle governs the paths light will take and explains the familiar phenomena of reflection, refraction, lenses and diffraction. Light rarely travels in a straight-line path. When photons interact with electrons in matter the time it takes for this interaction determines the path. For example, higher frequency blue light is refracted more than red because blue wavelengths interacts more frequently with electrons than red wavelengths and the path of least time is for blue to bend more then red in order to get out of this ‘slow’ area faster. The rainbows we see are a result of this. Fermat’s Principle explains the many fascinating phenomena of light from rainbows to sunsets to the haloes around the moon. |
Many enzymes require nonprotein helpers for what activity? | functional | hydrogen | kinetic | catalytic | |
What is often a result of untreated atherosclerosis? | seizures | cancer | heart disease | a heart attack or stroke | |
The hormones epinephrine and norepinephrine are released by what? | external medulla | uptake medulla | nutrients medulla | adrenal medulla | Short-term Stress Response When presented with a stressful situation, the body responds by calling for the release of hormones that provide a burst of energy. The hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) are released by the adrenal medulla. How do these hormones provide a burst of energy? Epinephrine and norepinephrine increase blood glucose levels by stimulating the liver and skeletal muscles to break down glycogen and by stimulating glucose release by liver cells. Additionally, these hormones increase oxygen availability to cells by increasing the heart rate and dilating the bronchioles. The hormones also prioritize body function by increasing blood supply to essential organs such as the heart, brain, and skeletal muscles, while restricting blood flow to organs not in immediate need, such as the skin, digestive system, and kidneys. Epinephrine and norepinephrine are collectively called catecholamines. |
How many possible alleles do the majority of human genes have? | less than four | three or more | two or less | two or more | The majority of human genes have two or more possible alleles. Differences in alleles account for the considerable genetic variation among people. In fact, most human genetic variation is the result of differences in individual DNA bases within alleles. |
What occurs during the new moon and full moon, due to gravitational pull? | spring storms | spring waves | spring floods | spring tides | Spring tides occur during the new moon and full moon. The Sun and Moon must either be in a straight line on the same side of Earth, or they must be on opposite sides of Earth. Their gravitational pull combines to cause very high and very low tides. Spring tides have the greatest tidal range. |
Alleles that carry deadly diseases are usually which type? | inherited | dominant | predominant | recessive | |
What releases fatty acids and other components from fats and phospholipids? | peristaltic hydrolysis | metabolism | enzyme respiration | enzymatic hydrolysis | |
What kind of energy comes from the position of a charged particle in an electric field? | thermal energy | solar energy | mechanical energy | potential energy | Electric potential energy comes from the position of a charged particle in an electric field. For example, when two negative charges are close together, they have potential energy because they repel each other and have the potential to push apart. If the charges actually move apart, their potential energy decreases. Electric charges always move spontaneously from a position where they have higher potential energy to a position where they have lower potential energy. This is like water falling over a dam from an area of higher to lower potential energy due to gravity. |
What does interstellar medium consist of? | dark matter | gravitational waves | the strong force | thinly spread gas and dust | Space may seem empty, but actually it contains thinly spread gas and dust, called interstellar medium, that gradually collapses over immense stretches of time and collects into denser clouds of gas and dust. The atoms of gas are mostly hydrogen and are typically about a centimeter apart. The dust is mostly carbon and silicon. In some places, this interstellar medium is collected into particularly dense clouds of gas and dust known as a nebula . A nebula is the birthplace of stars. Our sun was probably born in a nebula around 5 billion years ago. |
Sickle-cell disease significantly impairs the function of what? | metabolism system | limbic system | nervous system | circulatory system | |
What is the enlarged tip of the penis called? | outer penis | angles penis | testicular point | glans penis | The penis is an external genital organ with a long shaft and enlarged tip called the glans penis. The shaft of the penis contains erectile tissues that can fill with blood and cause an erection. When this occurs, the penis gets bigger and stiffer. The urethra passes through the penis. Sperm pass out of the body through the urethra. (During urination, the urethra carries urine from the bladder. ). |
What do you call the point at which the entire weight of a body may be considered to be concentrated? | direction of gravity | center of earth | complex of gravity | center of gravity | Every object has a center of gravity . The center of gravity is the point at which the entire weight of a body may be considered to be concentrated; if supported at this point, the body would remain in equilibrium in any position. For example, if we were discussing a 12-inch ruler, the center of gravity for the ruler would be at the center of the 6-inch line. You could put your finger directly under the 6-inch line to hold the ruler and it would not fall either left or right. If you placed your finger underneath any other place on the ruler, it would fall off to one side or the other. |
At how many places does points source pollution enter water? | four | three | two | one | Point source pollution enters water at just one place. For example, it might enter a stream through a pipe. Non-point source pollution enters water everywhere. It is carried by runoff. |
What do monarch butterfly larvae depend on for their food? | honey | seaweed | pollen | milkweeds | Another concern about biotechnology is how it may affect the environment. Negative effects on the environment have already occurred because of some GMOs. For example, corn has been created that has a gene for a pesticide. The corn plants have accidentally cross-pollinated nearby milkweeds. Monarch butterfly larvae depend on milkweeds for food. When they eat milkweeds with the pesticide gene, they are poisoned. This may threaten the survival of the monarch species as well as other species that eat monarchs. Do the benefits of the genetically modified corn outweigh the risks? What do you think?. |
As lava cools, tiny iron-rich crystals line up with earth’s what? | molecular field | gravitational field | oceans | magnetic field | Some rocks contain little compasses too! As lava cools, tiny iron-rich crystals line up with Earth’s magnetic field. Anywhere lavas have cooled, these magnetite crystals point to the magnetic poles. The little magnets point to where the north pole was when the lava cooled. Scientists can use this to figure out where the continents were at that time. This evidence clearly shows that the continents have moved. |
What do we call the amount of time a substance is stored in a reservoir? | presence time | storage time | latency | residence time | A substance is stored in a reservoir. The amount of time it stays in that reservoir is its residence time. |
Osmotic pressure is important in biological systems because cell walls are what? | variably membranes | impassable | theonym membranes | semipermeable membranes | Osmotic pressure is important in biological systems because cell walls are semipermeable membranes. In particular, when a person is receiving intravenous (IV) fluids, the osmotic pressure of the fluid needs to be approximately the same as blood serum; otherwise bad things can happen. Figure 11.4 "Osmotic Pressure and Red Blood Cells" shows three red blood cells: Figure 11.4 "Osmotic Pressure and Red Blood Cells"a shows a healthy red blood cell. Figure 11.4 "Osmotic Pressure and Red Blood Cells"b shows a red blood cell that has been exposed to a lower concentration than normal blood serum (a socalled hypotonic solution); the cell has plumped up as solvent moves into the cell to dilute the solutes inside. Figure 11.4 "Osmotic Pressure and Red Blood Cells"c shows a red blood cell exposed to a higher concentration than normal blood serum (hypertonic); water leaves the red blood cell, so it collapses onto itself. Only when the solutions inside and outside the cell are the same (isotonic) will the red blood cell be able to do its job. |
When does the diploid zygote form? | before the haploid zygote | never | before the pollen tube | after the pollen tube | Chapter 26 1 Figure 26.8 B. The diploid zygote forms after the pollen tube has finished forming, so that the male generative nuclei can fuse with the female gametophyte. 3 D 5 C 7 A 9 B 11 C 13 B 15 C 17 D 19 Both pollination and herbivory contributed to diversity, with plants needing to attract some insects and repel others. 21 The trees are adapted to arid weather, and do not lose as much water due to transpiration as non-conifers. 23 The resemblance between cycads and palm trees is only superficial. Cycads are gymnosperms and do not bear flowers or fruit. Cycads produce cones: large, female cones that produce naked seeds, and smaller male cones on separate plants. Palms do not. 25 Using animal pollinators promotes cross-pollination and increases genetic diversity. The odds that the pollen will reach another flower are greatly increased compared with the randomness of wind pollination. |
What is the minimum number of times a partial lunar eclipse will occur each year? | five | six | 11 | two | Partial lunar eclipses occur at least twice a year, but total lunar eclipses are less common. The Moon glows with a dull red coloring during a total lunar eclipse ( Figure below ). |
Microscopes were first developed in the early 1600s by this trade? | watch makers | food makers | polyurethane makers | eyeglass makers | Microscopes were first developed in the early 1600s by eyeglass makers in The Netherlands and Denmark. The simplest compound microscope is constructed from two convex lenses as shown schematically in Figure 26.16. The first lens is called the objective lens, and has typical magnification values from 5× to 100× . In standard microscopes, the objectives are mounted such that when you switch between objectives, the sample remains in focus. Objectives arranged in this way are described as parfocal. The second, the eyepiece, also referred to as the ocular, has several lenses which slide inside a cylindrical barrel. The focusing ability is provided by the movement of both the objective lens and the eyepiece. The purpose of a microscope is to magnify small objects, and both lenses contribute to the final magnification. Additionally, the final enlarged image is produced in a location far enough from the observer to be easily viewed, since the eye cannot focus on objects or images that are too close. |
What do we call the temperature at which a substance melts? | evaporation point | boiling point | precipitation point | melting point | The temperature at which a substance melts is called its melting point. The melting point of ice is 0°C. |
What is the small, dense region at the center of the atom that consists of positive protons and neutral neutrons? | photon | proton | electron | nucleus | The nucleus is a small, dense region at the center of the atom. It consists of positive protons and neutral neutrons, so it has an overall positive charge. |
By multiplying the force applied by the perpendicular component of the moment arm,what is determined? | pressure | radiation | intensities | torques | Individual torques are determined by multiplying the force applied by the perpendicular component of the moment arm. |
What carry messages from our sensory organs and others to the central nervous system? | blood vessels | fibers | valves | nerves | 20.7 Nerve Conduction–Electrocardiograms Nerve Conduction Electric currents in the vastly complex system of billions of nerves in our body allow us to sense the world, control parts of our body, and think. These are representative of the three major functions of nerves. First, nerves carry messages from our sensory organs and others to the central nervous system, consisting of the brain and spinal cord. Second, nerves carry messages from the central nervous system to muscles and other organs. Third, nerves transmit and process signals within the central nervous system. The sheer number of nerve cells and the incredibly greater number of connections between them makes this system the subtle wonder that it is. Nerve conduction is a general term for electrical signals carried by nerve cells. It is one aspect of bioelectricity, or electrical effects in and created by biological systems. Nerve cells, properly called neurons, look different from other cells—they have tendrils, some of them many centimeters long, connecting them with other cells. (See Figure 20.27. ) Signals arrive at the cell body across synapses or through dendrites, stimulating the neuron to generate its own signal, sent along its long axon to other nerve or muscle cells. Signals may arrive from many other locations and be transmitted to yet others, conditioning the synapses by use, giving the system its complexity and its ability to learn. |
What do you call the space around a charged particle where the particle exerts electric force on other charged particles? | charged field | melodic field | powered field | electric field | An electric field is a space around a charged particle where the particle exerts electric force on other charged particles. Because of their force fields, charged particles can exert force on each other without actually touching. Electric fields are generally represented by arrows, as you can see in the Figure below . The arrows show the direction of electric force around a positive particle and a negative particle. For an animated diagram, go to this URL: http://ocw. mit. edu/ans7870/8/8.02T/f04/visualizations/electrostatics/15-CreateField/CreateField_640. mpg. |
Natural convection is driven by what forces? | gravitational | magnetic | thermal | buoyant | sweating. These vessels become smaller when it is cold outside and larger when it is hot (so more fluid flows, and more energy is transferred). The body also loses a significant fraction of its heat through the breathing process. While convection is usually more complicated than conduction, we can describe convection and do some straightforward, realistic calculations of its effects. Natural convection is driven by buoyant forces: hot air rises because density decreases as temperature increases. The house in Figure 14.17 is kept warm in this manner, as is the pot of water on the stove in Figure 14.18. Ocean currents and large-scale atmospheric circulation transfer energy from one part of the globe to another. Both are examples of natural convection. |
Materials that can be magnetized are called? | inclusions materials | atoms materials | iron materials | ferromagnetic materials | In other materials, electrons fill the orbitals of the atoms that make up the material in a way to allow for each atom to have a tiny magnetic field, giving each atom a tiny north and south pole. There are large areas where the north and south poles of atoms are all lined up in the same direction. These areas are called magnetic domains . Generally, the magnetic domains point in different directions, so the material is still not magnetic. However, the material can be magnetized by placing it in a magnetic field. When this happens, all the magnetic domains become aligned, and the material becomes a magnet. This is illustrated in Figure below . Materials that can be magnetized are called ferromagnetic materials . They include iron, cobalt, and nickel. |
The overall purpose of the light-dependent reactions is to convert light energy into this? | calories | photosynthesis | thermal energy | chemical reactions | How Light-Dependent Reactions Work The overall purpose of the light-dependent reactions is to convert light energy into chemical energy. This chemical energy will be used by the Calvin cycle to fuel the assembly of sugar molecules. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. Photosystems exist in the membranes of thylakoids. A pigment molecule in the photosystem absorbs one photon, a quantity or “packet” of light energy, at a time. A photon of light energy travels until it reaches a molecule of chlorophyll. The photon causes an electron in the chlorophyll to become “excited. ” The energy given to the electron allows it to break free from an atom of the chlorophyll molecule. Chlorophyll is therefore said to “donate” an electron (Figure 5.12). To replace the electron in the chlorophyll, a molecule of water is split. This splitting releases an electron and results in the formation of oxygen (O2) and hydrogen ions (H+) in the thylakoid space. Technically, each breaking of a water molecule releases a pair of electrons, and therefore can replace two donated electrons. |
Jellyfish belong to which phylum? | mycobacteria | porifera | analidae | cnidaria | Do you know what these greenish, blob-like shapes are? Would it surprise you to learn that they are animals? They don’t look anything like the animals you are probably familiar with—animals such as dogs and deer, fish and frogs. But the greenish blobs are animals nonetheless. They belong to a phylum called Cnidaria, but you may know them as jellyfish. They are very simple animals and not fish at all. |
Along with changes in the shape of the resonant cavity, growth of what organ in pubescent boys leads to the difference in predominant frequencies in speech between men and women? | esoophagus | pharynx | trachea | larynx | The fundamental and overtones can be present simultaneously in a variety of combinations. For example, middle C on a trumpet has a sound distinctively different from middle C on a clarinet, both instruments being modified versions of a tube closed at one end. The fundamental frequency is the same (and usually the most intense), but the overtones and their mix of intensities are different and subject to shading by the musician. This mix is what gives various musical instruments (and human voices) their distinctive characteristics, whether they have air columns, strings, sounding boxes, or drumheads. In fact, much of our speech is determined by shaping the cavity formed by the throat and mouth and positioning the tongue to adjust the fundamental and combination of overtones. Simple resonant cavities can be made to resonate with the sound of the vowels, for example. (See Figure 17.30. ) In boys, at puberty, the larynx grows and the shape of the resonant cavity changes giving rise to the difference in predominant frequencies in speech between men and women. |
What intensifies the response during homeostasis? | negative feedback loops | pressure loops | pure loops | positive feedback loops | 1.5 Homeostasis Homeostasis is the activity of cells throughout the body to maintain the physiological state within a narrow range that is compatible with life. Homeostasis is regulated by negative feedback loops and, much less frequently, by positive feedback loops. Both have the same components of a stimulus, sensor, control center, and effector; however, negative feedback loops work to prevent an excessive response to the stimulus, whereas positive feedback loops intensify the response until an end point is reached. |
What is captured by the sticky structure at the top of the style called the stigma? | precipitation | fungi | sunlight | pollen | |
What is the term for a sac filled with fluid or other material? | tumor | blister | lesion | cyst | A common disorder of the ovaries is an ovarian cyst . A cyst is a sac filled with fluid or other material. An ovarian cyst is usually harmless, but it may cause pain. Most cysts slowly disappear and do not need treatment. Very large or painful cysts can be removed with surgery. |
What organ protects the body from injury, water loss, and microorganisms? | liver | heart | hair | skin | Skin protects the body from injury, water loss, and microorganisms. It also plays a major role in maintaining a stable body temperature. Common skin problems include acne and skin cancer. |
In which phase do the sister chromatids separate? | latent phase | prophase | passivation | anaphase | Anaphase is the phase in which the sister chromatids separate. The sister chromatids are pulled apart by the shortening of the microtubules of the spindles, similar to the reeling in of a fish by the shortening of the fishing line. One sister chromatid moves to one pole of the cell, and the other sister chromatid moves to the opposite pole. This process occurs when the proteins that bind sister chromatids together are cleaved, resulting in unattached identical chromosomes, essentially separate daughter chromosomes. These separate chromosomes are pulled apart by shortening spindle fibers, and pulled toward the centrosomes to which they are attached. At the end of anaphase the spindle fibers degrade. At this time, each pole of the cell has a complete set of chromosomes, identical to the amount of DNA at the beginning of G 1 of the cell cycle. |
Pinocytosis or "cellular drinking," occurs when the plasma membrane folds inward to form a channel allowing dissolved substances to enter what? | homeostasis | proteins | nucleus | cell | Pinocytosis or "cellular drinking," occurs when the plasma membrane folds inward to form a channel allowing dissolved substances to enter the cell, as shown in Figure below . When the channel is closed, the liquid is encircled within a pinocytic vesicle. |
Adult tunicates also develop a sac, called a what? | frill | hood | skirt | tunic | 24.2 Subphylum Urochordata The tunicates are located in this subphylum. Along with the subphylum Cephalochordata, these two subphyla make up the invertebrate chordates. Only the tunicate larvae have notochords, nerve cords, and postanal tails. Most adult tunicates are sessile, filter-feeders which retain their pharyngeal slits. Adult tunicates also develop a sac, called a tunic, which gives tunicates their name. Cilia beating within the turnicate cause water to enter the incurrent siphon. The water enters the body, passes through the pharyngeal slits, and leaves the body through the excurrent siphon. Undigested food is removed through the anus. Tunicates are hemaphrodites and can reproduce asexually through budding. In urochordates notochord is confined to larval tail. These lack cranium. These have an open type of circulatory system. Excretion is by neural gland,nephrocytes. |
What is the common measure of how hot or cold something is? | weight | variation | precipitation | temperature | temperature: A measure of the average kinetic energy of the particles in matter. In everyday usage, temperature is how hot or cold an object is. |
Aquatic biomes in the ocean are called what? | water biomes | aquiomes | tundra | marine biomes | Aquatic biomes in the ocean are called marine biomes. |
Oxygen reaches what veinless part of the eye by diffusing through its tear layer? | membranes | retina | pupil | cornea | 12.7 Molecular Transport Phenomena: Diffusion, Osmosis, and Related Processes 62. You can smell perfume very shortly after opening the bottle. To show that it is not reaching your nose by diffusion, calculate the average distance a perfume molecule moves in one second in air, given its diffusion constant D to be 1.00×10 –6 m 2 /s . What is the ratio of the average distances that oxygen will diffuse in a given time in air and water? Why is this distance less in water (equivalently, why is D less in water)? 64. Oxygen reaches the veinless cornea of the eye by diffusing through its tear layer, which is 0.500-mm thick. How long does it take the average oxygen molecule to do this? 65. (a) Find the average time required for an oxygen molecule to diffuse through a 0.200-mm-thick tear layer on the cornea. 3 (b) How much time is required to diffuse 0.500 cm of oxygen to the cornea if its surface area is 1.00 cm 2 ? 66. Suppose hydrogen and oxygen are diffusing through air. A small amount of each is released simultaneously. How much time passes before the hydrogen is 1.00 s ahead of the oxygen? Such differences in arrival times are used as an analytical tool in gas chromatography. |
Compound light microscopes use lenses to do what? | burn light | stop light | twist light | focus light | human body system that includes all the muscles of the body. |
What are the "code words" of the genetic code? | polymers | nucleotides | lipids | codons | Reading the Genetic Code. The genetic code is read three bases at a time. Codons are the code words of the genetic code. Which amino acid does codon 2 in the drawing stand for?. |
What processes allow for the greatest range of rotation within the vertebral column and facilitate the movement of the head? | anterior | vertical | lateral | articular | articular processes allow for the greatest range of rotation within the vertebral column. The lumbar region allows for considerable extension, flexion, and lateral flexion, but the orientation of the articular processes largely prohibits rotation. The articulations formed between the skull, the atlas (C1 vertebra), and the axis (C2 vertebra) differ from the articulations in other vertebral areas and play important roles in movement of the head. The atlanto-occipital joint is formed by the articulations between the superior articular processes of the atlas and the occipital condyles on the base of the skull. This articulation has a pronounced U-shaped curvature, oriented along the anterior-posterior axis. This allows the skull to rock forward and backward, producing flexion and extension of the head. This moves the head up and down, as when shaking your head “yes. ” The atlantoaxial joint, between the atlas and axis, consists of three articulations. The paired superior articular processes of the axis articulate with the inferior articular processes of the atlas. These articulating surfaces are relatively flat and oriented horizontally. The third articulation is the pivot joint formed between the dens, which projects upward from the body of the axis, and the inner aspect of the anterior arch of the atlas (Figure 9.14). A strong ligament passes posterior to the dens to hold it in position against the anterior arch. These articulations allow the atlas to rotate on top of the axis, moving the head toward the right or left, as when shaking your head “no. |
What property does coulomb electric force depend upon? | electric half | electric case | electric neutral | electric charge | Electromagnetism is associated with charge and is a fundamental force of nature, like gravity. If charges are static, the only manifestation of electromagnetism is the Coulomb electric force. In the same way that gravitational force depends on mass, the Coulomb electric force depends on the property known as electric charge. Like gravity, the Coulomb electric Force decreases with the square of the distance. The Coulomb electric force is responsible for many of the forces we discussed previously: the normal force, contact forces such as friction, and so on - all of these forces arise in the mutual attraction and repulsion of charged particles. |
What is the process of changing something from a gas to a liquid? | fermentation | sublimation | combustion | condensation | Condensation is the change of state from a gas to a liquid. |
What are the two divisions of vascular plants? | aquatic and terrestrial | root and seed | seedless and semi-seeded | seedless and seed | The most basic division of living plants is between nonvascular and vascular plants. Vascular plants are further divided into seedless and seed plants. Seed plants called gymnosperms produce seeds in cones. Seed plants called angiosperms produce seeds in the ovaries of flowers. |
What contains carbon, hydrogen, and oxygen in a ratio of 1:2:1? | magnesium | helium | sodium | carbohydrate | The term carbohydrate comes from the fact that the majority contain carbon, hydrogen, and oxygen in a ratio of 1:2:1, making for an empirical formula of CH 2 O. This is somewhat misleading because the molecules are not actually hydrates of carbon at all. Carbohydrates are monomers and polymers of aldehydes and ketones that have multiple hydroxyl groups attached. |
During interphase of what process, each chromosome is duplicated, and the sister chromatids formed during synthesis are held together at the centromere region by cohesin proteins? | digestion | mitosis | apoptosis | meiosis | Chapter 11 1 Figure 11.9 Yes, it will be able to reproduce asexually. 2 C 4 D 6 C 8 C 10 C 12 B 14 During the meiotic interphase, each chromosome is duplicated. The sister chromatids that are formed during synthesis are held together at the centromere region by cohesin proteins. All chromosomes are attached to the nuclear envelope by their tips. As the cell enters prophase I, the nuclear envelope begins to fragment, and the proteins holding homologous chromosomes locate each other. The four sister chromatids align lengthwise, and a protein lattice called the synaptonemal complex is formed between them to bind them together. The synaptonemal complex facilitates crossover between non-sister chromatids, which is observed as chiasmata along the length of the chromosome. As prophase I progresses, the synaptonemal complex breaks down and the sister chromatids become free, except where they are attached by chiasmata. At this stage, the four chromatids are visible in each homologous pairing and are called a tetrad. 16 In metaphase I, the homologous chromosomes line up at the metaphase plate. In anaphase I, the homologous chromosomes are pulled apart and move to opposite poles. Sister chromatids are not separated until meiosis II. The fused kinetochore formed during meiosis I ensures that each spindle microtubule that binds to the tetrad will attach to both sister chromatids. 18 a. Crossover occurs in prophase I between non-sister homologous chromosomes. Segments of DNA are exchanged between maternally derived and paternally derived chromosomes, and new gene combinations are formed. Random alignment during metaphase I leads to gametes that have a mixture of maternal and paternal chromosomes. Fertilization is random, in that any two gametes can fuse. |
Like animals, cyanobacteria possess what kind of biological rhythm? | variable rhythm | brain rhythm | music rhythm | circadian rhythm | |
The ocean is the largest marine biome. it is a continuous body of salt water that is relatively uniform in chemical composition; it is a weak solution of mineral salts and decayed what? | metal ores | uranium atoms | rock shards | biological matter | Marine Biomes The ocean is the largest marine biome. It is a continuous body of salt water that is relatively uniform in chemical composition; it is a weak solution of mineral salts and decayed biological matter. Within the ocean, coral reefs are a second kind of marine biome. Estuaries, coastal areas where salt water and fresh water mix, form a third unique marine biome. Ocean The physical diversity of the ocean is a significant influence on plants, animals, and other organisms. The ocean is categorized into different zones based on how far light reaches into the water. Each zone has a distinct group of species adapted to the biotic and abiotic conditions particular to that zone. The intertidal zone, which is the zone between high and low tide, is the oceanic region that is closest to land (Figure 44.21). Generally, most people think of this portion of the ocean as a sandy beach. In some cases, the intertidal zone is indeed a sandy beach, but it can also be rocky or muddy. The intertidal zone is an extremely variable environment because of tides. Organisms are exposed to air and sunlight at low tide and are underwater most of the time, especially during high tide. Therefore, living things that thrive in the intertidal zone are adapted to being dry for long periods of time. The shore of the intertidal zone is also repeatedly struck by waves, and the organisms found there are adapted to withstand damage from the pounding action of the waves (Figure 44.22). The exoskeletons of shoreline crustaceans (such as the shore crab, Carcinus maenas) are tough and protect them from desiccation (drying out) and wave damage. Another consequence of the pounding waves is that few algae and plants establish themselves in the constantly moving rocks, sand, or mud. |
What two tubes extend from the upper corners of the uterus? | ovary | Cervical | ovarian | fallopian | Extending from the upper corners of the uterus are the two fallopian tubes . Each tube reaches (but is not attached to) one of the ovaries. The ovary end of the tube has a fringelike structure that moves in waves. The motion sweeps eggs from the ovary into the tube. |
What term describes a wave in which particles of the medium vibrate at right angles, or perpendicular, to the direction that the wave travels? | stimulation wave | drainage wave | symmetrical wave | transverse wave | A transverse wave is a wave in which particles of the medium vibrate at right angles, or perpendicular, to the direction that the wave travels. Another example of a transverse wave is the wave that passes through a rope with you shake one end of the rope up and down, as in the Figure below . The direction of the wave is down the length of the rope away from the hand. The rope itself moves up and down as the wave passes through it. You can watch a video of a transverse wave in a rope at this URL: http://www. youtube. com/watch?v=TZIr9mpERbU . |
Exemplified by rusty iron, what process is defined as the disintegration of a material due to chemical reactions with other substances in the environment? | extraction | Metal Breakdown | magnesium | corrosion | Most of us are familiar with rusty iron: metal that has a dark red-brown scale that falls off an object, ultimately weakening it. Although we usually attribute rusting exclusively to iron, this process occurs with many materials. The more formal term for rusting is corrosion. Corrosion is defined as the disintegration of a material due to chemical reactions with other substances in the environment. In many cases, oxygen in the air causes the disintegration. Corrosion is not uniformly destructive. Although the corrosion of iron is generally considered bad, the corrosion of aluminum and copper forms a protective barrier on the surface of the metal, protecting it from further reaction with the environment. Having said that, it has been estimated that as much as 5% of expenditures in the United States apply to fixing problems caused by corrosion. The replacement of structures built with iron, steel, aluminum, and concrete must be performed regularly to keep these structures safe. As an example of what might happen, consider the story of the Silver Bridge on US Interstate 35, connecting West Virginia and Ohio. On December 15, 1967, the 39-year-old bridge collapsed, killing 46 people. The ultimate cause of the collapse was determined to be corrosion of a suspension chain on the Ohio side of the bridge. Corrosion is an example of the type of chemical reaction discussed in this chapter. Although we usually think of corrosion as bad, the reaction it typifies can actually be put to good use. One important type of chemical reaction is the oxidation-reduction reaction, also known as the redox reaction. Although we introduced redox reactions in - ball-ch04, - ball-ch04_s06, it is worth reviewing some basic concepts. |
What is a renewable resource that can take thousand of years to form? | water | sunlight | wind | soil | Soil is a renewable resource, but it can take thousands of years to form. That’s why people need to do what they can to prevent soil erosion. |
Impenetrable what underlies the soil of the forest? | groundwater | structure | topsoil | bedrock | |
What is the term for when two opposing processes reach the same speed, resulting in no overall change? | homeostasis | neutralization | acceleration | equilibrium | Imagine you are stranded in a rowboat in the middle of the ocean. Suddenly, your boat springs a small leak, and you need to bail out water. You grab a bucket and begin to bail. After a few minutes, your efforts against the leak keep the water to only about half an inch, but any further bailing doesn’t change the water level; the leak brings in as much water as you bail out. You are at equilibrium. Two opposing processes have reached the same speed, and there is no more overall change in the process. Chemical reactions are like that as well. Most of them come to an equilibrium. The actual position of the equilibrium—whether it favors the reactants or the products—is characteristic of a chemical reaction; it is difficult to see just by looking at the balanced chemical equation. But chemistry has tools to help you understand the equilibrium of chemical reactions—the focus of our study in this chapter. So far in this text, when we present a chemical reaction, we have implicitly assumed that the reaction goes to completion. Indeed, our stoichiometric calculations were based on this; when we asked how much of a product is produced when so much of a reactant reacts, we are assuming that all of a reactant reacts. However, this is usually not the case; many reactions do not go to completion, and many chemists have to deal with that. In this chapter, we will study this phenomenon and see ways in which we can affect the extent of chemical reactions. |
What term describes the number and kinds of species in a location or on the planet? | ecosystem | habitat | Allopatric speciation | biodiversity | Types of Biodiversity Scientists generally accept that the term biodiversity describes the number and kinds of species in a location or on the planet. Species can be difficult to define, but most biologists still feel comfortable with the concept and are able to identify and count eukaryotic species in most contexts. Biologists have also identified alternate measures of biodiversity, some of which are important for planning how to preserve biodiversity. Genetic diversity is one of those alternate concepts. Genetic diversity or variation is the raw material for adaptation in a species. A species’ future potential for adaptation depends on the genetic diversity held in the genomes of the individuals in populations that make up the species. The same is true for higher taxonomic categories. A genus with very different types of species will have more genetic diversity than a genus with species that look alike and have similar ecologies. If there were a choice between one of these genera of species being preserved, the one with the greatest potential for subsequent. |
What energy is stored in a person or object? | stored energy | kinetic energy | mechanical energy | potential energy | The diver has energy because of her position high above the pool. The type of energy she has is called potential energy. Potential energy is energy that is stored in a person or object. Often, the person or object has potential energy because of its position or shape. |
What do we call a peptide hormone composed of nine amino acids that lowers blood pressure? | bufotenin | angiotensin | parcnid | bradykinin | Bradykinin is a peptide hormone composed of nine amino acids that lowers blood pressure. Its primary structure is arg-pro-pro-gly-phe-ser-pro-phe-arg. Would you expect bradykinin to be positively charged, negatively charged, or neutral at a pH of 6.0? Justify your answer. |
Which lymphoid organ is situated in the upper chest? | pancreas | thyroid gland | spleen | thymus | The thymus is located in the upper chest behind the breast bone. It stores and matures lymphocytes. |
What is calculated by subtracting the smallest value from the largest value? | the median | the sample | the density | the range | The range is the total spread of values. It gives you an idea of the variation in the measurements. The range is calculated by subtracting the smallest value from the largest value. For the data in Table above , the range in numbers of vehicles by type is: 150 - 50 = 100. |
Birds actually have two basic types of feathers: flight feathers and? | shed feathers | colorful plumes | landing feathers | down feathers | Feathers help birds fly and also provide insulation and serve other purposes. Birds actually have two basic types of feathers: flight feathers and down feathers. Both are shown in Figure below . Flight feathers are long, stiff, and waterproof. They provide lift and air resistance without adding weight. Down feathers are short and fluffy. They trap air next to a bird’s skin for insulation. |
What is the name for the process of charging an object by touching it with another charged object? | charging by transfer | charging by connection | charging by convection | charging by conduction | Charging an object by touching it with another charged object is called charging by conduction. By bringing a charged object into contact with an uncharged object, some electrons will migrate to even out the charge on both objects. Charging by conduction gives the previously uncharged object a permanent charge. An uncharged object can also be charged using a method called charging by induction . This process allows a change in charge without actually touching the charged and uncharged objects to each other. Imagine a negatively charged rod held near the knob, but not touching. If we place a finger on the knob, some of the electrons will escape into our body, instead of down the stem and into the leaves. When both our finger and the negatively charged rod are removed, the previously uncharged electroscope now has a slight positive charge. It was charged by induction. Notice that charging by induction causes the newly charged object to have the opposite charge as the originally charged object, while charging by conduction gives them both the same charge. |
Labor is the muscular contractions to expel the fetus and placenta from where? | tumors | lungs | anus | uterus | Visit this website (http://openstaxcollege. org/l/embryo_fetus2) to see the stages of human fetal development. Labor is the muscular contractions to expel the fetus and placenta from the uterus. Toward the end of the third trimester, estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin. At this time, the baby reorients, facing forward and down with the back or crown of the head engaging the cervix (uterine opening). This causes the cervix to stretch and nerve impulses are sent to the hypothalamus, which signals the release of oxytocin from the posterior pituitary. Oxytocin causes smooth muscle in the uterine wall to contract. At the same time, the placenta releases prostaglandins into the uterus, increasing the contractions. A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin. As more smooth muscle cells are recruited, the contractions increase in intensity and force. There are three stages to labor. During stage one, the cervix thins and dilates. This is necessary for the baby and placenta to be expelled during birth. The cervix will eventually dilate to about 10 cm. During stage two, the baby is expelled from the uterus. The uterus contracts and the mother pushes as she compresses her abdominal muscles to aid the delivery. The last stage is the passage of the placenta after the baby has been born and the organ has completely disengaged from the uterine wall. If labor should stop before stage two is reached, synthetic oxytocin, known as Pitocin, can be administered to restart and maintain labor. |
What are topographic maps that show water depths called? | Water Table maps | solenoid maps | morainic maps | bathymetric maps | Topographic maps that show water depths are called bathymetric maps . An example of one is pictured below ( Figure below ). Bathymetric maps are made of any water body, including lakes and oceans. On these maps, the contour lines represent depth below the surface. Therefore, high numbers are deeper depths and low numbers are shallow depths. |
What is the radula made mostly of? | schist | casein | chlorophyll | chitin | Many species have a feeding structure, the radula , found only in mollusks. The radula can be thought of as a "tongue-like" structure. The radula is made mostly of chitin. Types of radulae range from structures used to scrape algae off of rocks to the beaks of squid and octopuses. |
Energy transferred solely due to a temperature difference is called? | humidity | chemical energy | magnetic energy | heat | Heat and work are the two distinct methods of energy transfer. Heat is energy transferred solely due to a temperature difference. Any energy unit can be used for heat transfer, and the most common are kilocalorie (kcal) and joule (J). Kilocalorie is defined to be the energy needed to change the temperature of 1.00 kg of water between 14.5ºC and. |
In which organ does a baby develop? | ovaries | pelvis | pancreas | uterus | The uterus is a hollow organ with muscular walls. The uterus is where a baby develops until birth. The walls of the uterus stretch to accommodate the growing fetus. The muscles in the walls contract to push the baby out during birth. The uterus is connected to the vagina by a small opening called the cervix. |
What part of an experiment or other investigation consists of the individuals or events that are studied? | independent variable | hypothesis | experimental control | sample | The sample in an experiment or other investigation consists of the individuals or events that are studied. Typically, the sample is much smaller than all such individuals or events that exist in the world. Whether the results based on the sample are true in general cannot be known for certain. However, the larger the sample is, the more likely it is that the results are generally true. Similarly, the more times that an experiment is repeated and the same results obtained, the more likely the results are valid. This is why scientific experiments should always be repeated. |
The intentional release or spread of agents of disease is known as what? | disaster | act of war | pandemic | bioterrorism | Bioterrorism is the intentional release or spread of agents of disease. The agents may be viruses, bacteria, or toxins produced by bacteria. The agents may spread through the air, food, or water; or they may come into direct contact with the skin. Two of the best known bioterrorism incidents in the U. S. occurred early in this century:. |
If pressure is exerted on the rock from one direction, the rock forms layers. this is called what? | sedimentation | protonation | stratification | foliation | During metamorphism, a rock may change chemically. Ions move in or out of a mineral. This creates a different mineral. The new minerals that form during metamorphism are more stable in the new environment. Extreme pressure may lead to physical changes. If pressure is exerted on the rock from one direction, the rock forms layers. This is foliation . If pressure is exerted from all directions, the rock usually does not show foliation. |
What term is used to describe the average weather of a place over many years? | meteorology | atmosphere | landscape | climate | Climate is the average weather of a place over many years. It includes average temperatures. It also includes average precipitation. The timing of precipitation is part of climate as well. What determines the climate of a place? Latitude is the main factor. A nearby ocean or mountain range can also play a role. |
A long chain of monosaccharides linked by glycosidic bonds is known as what? | polymers | sulfate | Fructose | polysaccharide | Polysaccharides A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide (poly- = “many”). The chain may be branched or unbranched, and it may contain different types of monosaccharides. The molecular weight may be 100,000 daltons or more depending on the number of monomers joined. Starch, glycogen, cellulose, and chitin are primary examples of polysaccharides. Starch is the stored form of sugars in plants and is made up of a mixture of amylose and amylopectin (both polymers of glucose). Plants are able to synthesize glucose, and the excess glucose, beyond the plant’s immediate energy needs, is stored as starch in different plant parts, including roots and seeds. The starch in the seeds provides food for the embryo as it germinates and can also act as a source of food for humans and animals. The starch that is consumed by humans is broken down by enzymes, such as salivary amylases, into smaller molecules, such as maltose and glucose. The cells can then absorb the glucose. Starch is made up of glucose monomers that are joined by α 1-4 or α 1-6 glycosidic bonds. The numbers 1-4 and 1-6 refer to the carbon number of the two residues that have joined to form the bond. As illustrated in Figure 3.9, amylose is starch formed by unbranched chains of glucose monomers (only α 1-4 linkages), whereas amylopectin is a branched polysaccharide (α 1-6 linkages at the branch points). |
How do genes located on separate nonhomologous chromosomes sort? | typically | mechanically | intradependently | independently | Linked Genes Violate the Law of Independent Assortment Although all of Mendel’s pea characteristics behaved according to the law of independent assortment, we now know that some allele combinations are not inherited independently of each other. Genes that are located on separate nonhomologous chromosomes will always sort independently. However, each chromosome contains hundreds or thousands of genes, organized linearly on chromosomes like beads on a string. The segregation of alleles into gametes can be influenced by linkage, in which genes that are located physically close to each other on the same chromosome are more likely to be inherited as a pair. However, because of the process of recombination, or “crossover,” it is possible for two genes on the same chromosome to behave independently, or as if they are not linked. To understand this, let’s consider the biological basis of gene linkage and recombination. Homologous chromosomes possess the same genes in the same linear order. The alleles may differ on homologous chromosome pairs, but the genes to which they correspond do not. In preparation for the first division of meiosis, homologous chromosomes replicate and synapse. Like genes on the homologs align with each other. At this stage, segments of homologous chromosomes exchange linear segments of genetic material (Figure 12.18). This process is called recombination, or crossover, and it is a common genetic process. Because the genes are aligned during recombination, the gene order is not altered. Instead, the result of recombination is that maternal and paternal alleles are combined onto the same chromosome. Across a given chromosome, several recombination events may occur, causing extensive shuffling of alleles. |
What type of mass movement is a sudden movement of large blocks of rock and soil down a slope? | downturn | deluge | resurgence | slump | Two other types of mass movement are slump and creep. They usually aren’t as destructive as landslides and mudslides. Slump is the sudden movement of large blocks of rock and soil down a slope. Creep is the very slow movement of rock and soil down a slope. It causes trees, fence posts, and other structures to tilt downhill. |
What consists of structures that produce eggs and secrete female sex hormones? | asexual reproductive system | male reproductive system | female neural system | female reproductive system | The female reproductive system consists of structures that produce eggs and secrete female sex hormones. They also provide a site for fertilization and enable the development and birth of a fetus. They include the vagina, uterus, ovaries, and fallopian tubes. |
Lactic acid fermentation is common in muscle cells that have run out of what? | nitrogen | carbon | helium | oxygen | Figure 7.14 Lactic acid fermentation is common in muscle cells that have run out of oxygen. |
How many sets of chromosomes does each somatic cell have? | six | one | four | two | Each human somatic cell (a body cell, or every cell other than a gamete) normally has two sets of chromosomes, one set inherited from each parent. These cells are said to have a diploid number of chromosomes. Each set contains 23 chromosomes, for a total of 46 chromosomes. Each chromosome differs in size, from about 250 million nucleotide pairs on the largest chromosome (chromosome #1) to less than 50 million nucleotide pairs on chromosome #22. Each chromosome contains a specific set of genes, as well as regulatory elements and other nucleotide sequences, making each chromosome essential to survival. |
Nonflowering vascular plants have three basic types of leaves: microphylls, fronds, and what other type? | stems | molds | tubes | needles | Leaves may vary in size, shape, and their arrangement on stems. Nonflowering vascular plants have three basic types of leaves: microphylls (“tiny leaves”), fronds, and needles. Figure below describes each type. |
What is the most common plant-like protist? | esoteric algae | mundane algae | invasive algae | unicellular algae | Ginkgoes, like cycads, has separate female and male plants. The male trees are usually preferred for landscaping because the seeds produced by the female plants smell terrible when they ripen. |
What biochemicals mediate changes in target cells by binding to specific receptors? | enzymes | amino acids | acids | hormones | 37.2 | How Hormones Work By the end of this section, you will be able to: • Explain how hormones work • Discuss the role of different types of hormone receptors Hormones mediate changes in target cells by binding to specific hormone receptors. In this way, even though hormones circulate throughout the body and come into contact with many different cell types, they only affect cells that possess the necessary receptors. Receptors for a specific hormone may be found on many different cells or may be limited to a small number of specialized cells. For example, thyroid hormones act on many different tissue types, stimulating metabolic activity throughout the body. Cells can have many receptors for the same hormone but often also possess receptors for different types of hormones. The number of receptors that respond to a hormone determines the cell’s sensitivity to that hormone, and the resulting cellular response. Additionally, the number of receptors that respond to a hormone can change over time, resulting in increased or decreased cell sensitivity. In up-regulation, the number of receptors increases in response to rising hormone levels, making the cell more sensitive to the hormone and allowing for more cellular activity. When the number of receptors decreases in response to rising hormone levels, called down-regulation, cellular activity is reduced. Receptor binding alters cellular activity and results in an increase or decrease in normal body processes. Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signaling pathways. |
New land can be created when what happens to a volcano? | it stays dormant | it evolves | it dies | it erupts | New land can be created by volcanic eruptions. |
To calculate acceleration without a change in direction, you just divide the change in velocity by the change in what? | size | weight | height | time | Calculating acceleration is complicated if both speed and direction are changing. It’s easier to calculate acceleration when only speed is changing. To calculate acceleration without a change in direction, you just divide the change in velocity (represented by ) by the change in time (represented by ). The formula for acceleration in this case is:. |
What is reduced and forms part of the gelatinous disks sandwiched between the vertebrae in humans? | the pelvis | the clavicle | the sacrum | the notochord | |
What type of relationship is parasitism? | hypodermic relationship | primordial relationship | enzymatic relationship | symbiotic relationship | Parasitism is a symbiotic relationship in which one species benefits and the other species is harmed. The species that benefits is called the parasite. The species that is harmed is called the host. Many species of animals are parasites, at least during some stage of their life cycle. Most animal species are also hosts to one or more parasites. |
What two things are used in optical instruments to reflect or refract light? | prisms and microscopes | orientations and lenses | mirrors and magnifiers | mirrors and lenses | Mirrors and lenses are used in optical instruments to reflect or refract light. Optical instruments include microscopes, telescopes, cameras, and lasers. |
What physical property of matter reflects how closely packed the particles of matter are? | mass | makeup | build up | density | Density is an important physical property of matter. It reflects how closely packed the particles of matter are. |
What type of boiling point do nonmetals normally have? | odd | even | high | low | Properties of nonmetals include a relatively low boiling point, so many nonmetals are gases. Nonmetals are also poor conductors of heat, and solid nonmetals are dull and brittle. |
Coxal glands collect liquid waste from what? | heart | lungs | plasma | blood | Some arthropods have special excretory structures. They are called coxal glands and Malpighian tubules . Coxal glands collect and concentrate liquid waste from blood. They excrete the waste from the body through a pore. Malphigian tubules carry waste from the digestive tract to the anus. The waste is excreted through the anus. |
The main organs of the cardiovascular system are the blood vessels and what else? | lung | alveoli | capillaries | heart | The main organs of the cardiovascular system are the heart and blood vessels. Both organs contain valves. Valves also are found in plumbing systems. They can be turned on or off to control the flow of water. |
What substance flows over the land from precipitation or melting snow or ice? | air | nitrogen | lava | water | water that flows over the land from precipitation or melting snow or ice. |
Most turtle bodies are covered by a special bony or cartilaginous shell developed from their what? | fins | spines | tails | ribs | Most turtle bodies are covered by a special bony or cartilaginous shell developed from their ribs. |
What device uses an electromagnet to change electrical energy to kinetic energy? | Magnetic motor. | public motor | melodic motor | electric motor | An electric motor is a device that uses an electromagnet to change electrical energy to kinetic energy. When current flows through the motor, the electromagnet rotates, causing a shaft to rotate as well. The rotating shaft moves other parts of the device. |