Answer: biofilms

Context: Bacteria often attach to surfaces and form dense aggregations called biofilms or bacterial mats. These films can range from a few micrometers in thickness to up to half a meter in depth, and may contain multiple species of bacteria, protists and archaea. Bacteria living in biofilms display a complex arrangement of cells and extracellular components, forming secondary structures, such as microcolonies, through which there are networks of channels to enable better diffusion of nutrients. In natural environments, such as soil or the surfaces of plants, the majority of bacteria are bound to surfaces in biofilms. Biofilms are also important in medicine, as these structures are often present during chronic bacterial infections or in infections of implanted medical devices, and bacteria protected within biofilms are much harder to kill than individual isolated bacteria.

Question: What does bacteria use to adhere to surfaces?


Answer: up to half a meter in depth

Question: How extent can biofilm be?


Answer: microcolonies,

Question: What is part of secondary structure in the complex formation of bacteria?


Answer: to enable better diffusion of nutrients

Question: What is the purpose of networks of channels in microcolonies?


Answer: bacteria protected within biofilms

Question: Which bacteria is more difficult to eradicate?


Answer: amino acids

Context: Even more complex morphological changes are sometimes possible. For example, when starved of amino acids, Myxobacteria detect surrounding cells in a process known as quorum sensing, migrate toward each other, and aggregate to form fruiting bodies up to 500 micrometres long and containing approximately 100,000 bacterial cells. In these fruiting bodies, the bacteria perform separate tasks; this type of cooperation is a simple type of multicellular organisation. For example, about one in 10 cells migrate to the top of these fruiting bodies and differentiate into a specialised dormant state called myxospores, which are more resistant to drying and other adverse environmental conditions than are ordinary cells.

Question: What is the vital nutriment for Myxobacteria?


Answer: aggregate to form fruiting bodies

Question: Why do cells of Myxobacteria migrate towards each other?


Answer: more resistant

Question: How hard to treat bacteria cells in a passive state?


Answer: multicellular organisation

Question: What bacteria do in fruiting bodies?


Answer: lipid

Context: The bacterial cell is surrounded by a cell membrane (also known as a lipid, cytoplasmic or plasma membrane). This membrane encloses the contents of the cell and acts as a barrier to hold nutrients, proteins and other essential components of the cytoplasm within the cell. As they are prokaryotes, bacteria do not usually have membrane-bound organelles in their cytoplasm, and thus contain few large intracellular structures. They lack a true nucleus, mitochondria, chloroplasts and the other organelles present in eukaryotic cells. Bacteria were once seen as simple bags of cytoplasm, but structures such as the prokaryotic cytoskeleton and the localization of proteins to specific locations within the cytoplasm that give bacteria some complexity have been discovered. These subcellular levels of organization have been called "bacterial hyperstructures".

Question: What is a cell membrane?


Answer: barrier to hold nutrients, proteins and other essential components

Question: What does membrane accomplish?


Answer: do not

Question: Do bacteria have membrabe-bound organelles in their cytoplasm?


Answer: true nucleus, mitochondria, chloroplasts and the other organelles

Question: Absence of what make bacteria belong to prokaryotes?


Answer: simple bags of cytoplasm

Question: What bacteria was observed as before prokaryotic cytoskeleton was discovered?


Answer: concentration gradients across membranes

Context: Many important biochemical reactions, such as energy generation, use concentration gradients across membranes. The general lack of internal membranes in bacteria means reactions such as electron transport occur across the cell membrane between the cytoplasm and the periplasmic space. However, in many photosynthetic bacteria the plasma membrane is highly folded and fills most of the cell with layers of light-gathering membrane. These light-gathering complexes may even form lipid-enclosed structures called chlorosomes in green sulfur bacteria. Other proteins import nutrients across the cell membrane, or expel undesired molecules from the cytoplasm.

Question: What is crucial for biochemical reactions?


Answer: light-gathering membrane

Question: What kind of membrane do bacteria cells are filled with?


Answer: between the cytoplasm and the periplasmic space

Question: How does electron transit occur in bacteria?


Answer: light-gathering complexes may even form lipid-enclosed structures

Question: Can membrane of bacteria create lipid structure?


Answer: a single circular DNA chromosome

Context: Bacteria do not have a membrane-bound nucleus, and their genetic material is typically a single circular DNA chromosome located in the cytoplasm in an irregularly shaped body called the nucleoid. The nucleoid contains the chromosome with its associated proteins and RNA. The phylum Planctomycetes and candidate phylum Poribacteria may be exceptions to the general absence of internal membranes in bacteria, because they appear to have a double membrane around their nucleoids and contain other membrane-bound cellular structures. Like all living organisms, bacteria contain ribosomes, often grouped in chains called polyribosomes, for the production of proteins, but the structure of the bacterial ribosome is different from that of eukaryotes and Archaea. Bacterial ribosomes have a sedimentation rate of 70S (measured in Svedberg units): their subunits have rates of 30S and 50S. Some antibiotics bind specifically to 70S ribosomes and inhibit bacterial protein synthesis. Those antibiotics kill bacteria without affecting the larger 80S ribosomes of eukaryotic cells and without harming the host.

Question: What is genetic make of bacteria?


Answer: in the cytoplasm

Question: Where is DNA chromosome of bacteria located?


Answer: irregularly shaped body

Question: How does nucleoid look?


Answer: phylum Planctomycetes and candidate phylum Poribacteria

Question: What are the exceptions of non-internal membrane bacteria?


Answer: production of proteins

Question: What is the purpose of polyribosomes in bacteria?


Answer: glycogen, polyphosphate, sulfur or polyhydroxyalkanoates

Context: Some bacteria produce intracellular nutrient storage granules for later use, such as glycogen, polyphosphate, sulfur or polyhydroxyalkanoates. Certain bacterial species, such as the photosynthetic Cyanobacteria, produce internal gas vesicles, which they use to regulate their buoyancy – allowing them to move up or down into water layers with different light intensities and nutrient levels. Intracellular membranes called chromatophores are also found in membranes of phototrophic bacteria. Used primarily for photosynthesis, they contain bacteriochlorophyll pigments and carotenoids. An early idea was that bacteria might contain membrane folds termed mesosomes, but these were later shown to be artifacts produced by the chemicals used to prepare the cells for electron microscopy. Inclusions are considered to be nonliving components of the cell that do not possess metabolic activity and are not bounded by membranes. The most common inclusions are glycogen, lipid droplets, crystals, and pigments. Volutin granules are cytoplasmic inclusions of complexed inorganic polyphosphate. These granules are called metachromatic granules due to their displaying the metachromatic effect; they appear red or blue when stained with the blue dyes methylene blue or toluidine blue. Gas vacuoles, which are freely permeable to gas, are membrane-bound vesicles present in some species of Cyanobacteria. They allow the bacteria to control their buoyancy. Microcompartments are widespread, membrane-bound organelles that are made of a protein shell that surrounds and encloses various enzymes. Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation. Magnetosomes are bacterial microcompartments, present in magnetotactic bacteria, that contain magnetic crystals.

Question: What types of intracellar nutrient can bacteria produce?


Answer: to control their buoyancy

Question: What gas vacuoles are respoonsible for in bacteria?


Answer: glycogen, lipid droplets, crystals, and pigments

Question: What are the most common nonliving compositions in bacteria?


Answer: move up or down into water layers with different light intensities

Question: How does gas vesicles produced by Cyanobacteria help her to move in water?


Answer: photosynthesis

Question: What are chromatophores used for?


Answer: cell membrane and cell wall

Context: In most bacteria, a cell wall is present on the outside of the cell membrane. The cell membrane and cell wall comprise the cell envelope. A common bacterial cell wall material is peptidoglycan (called "murein" in older sources), which is made from polysaccharide chains cross-linked by peptides containing D-amino acids. Bacterial cell walls are different from the cell walls of plants and fungi, which are made of cellulose and chitin, respectively. The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, and the antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan.

Question: What composes the cell envelope?


Answer: peptidoglycan

Question: What is most common cell wall material?


Answer: Bacterial cell walls are different

Question: Are cell walls of bacteria similar to cell walls of plants and fungi?


Answer: by inhibiting a step in the synthesis of peptidoglycan

Question: How can antibiotic penicillin destroy bacteria?


Answer: cellulose and chitin

Question: What are the main materials of cell walls of plants and fungi?


Answer: thick cell wall containing many layers of peptidoglycan and teichoic acids

Context: Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Lipopolysaccharides, also called endotoxins, are composed of polysaccharides and lipid A that is responsible for much of the toxicity of gram-negative bacteria. Most bacteria have the gram-negative cell wall, and only the Firmicutes and Actinobacteria have the alternative gram-positive arrangement. These two groups were previously known as the low G+C and high G+C Gram-positive bacteria, respectively. These differences in structure can produce differences in antibiotic susceptibility; for instance, vancomycin can kill only gram-positive bacteria and is ineffective against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa. If the bacterial cell wall is entirely removed, it is called a protoplast, whereas if it is partially removed, it is called a spheroplast. β-Lactam antibiotics, such as penicillin, inhibit the formation of peptidoglycan cross-links in the bacterial cell wall. The enzyme lysozyme, found in human tears, also digests the cell wall of bacteria and is the body's main defense against eye infections.

Question: What does gram-positive bacteria have?


Answer: polysaccharides and lipid A

Question: Why gram-negative cell bacteria is more toxic than gram-positive bacteria?


Answer: Lipopolysaccharides

Question: What can be endotoxins called?


Answer: differences in antibiotic susceptibility

Question: What can different structure of the cell walls of bacteria effect?


Answer: enzyme lysozyme, found in human tears

Question: What is the main defense of human body against eye infections?


Answer: Ziehl-Neelsen stain

Context: Acid-fast bacteria, such as Mycobacteria, are resistant to decolorization by acids during staining procedures. The high mycolic acid content of Mycobacteria, is responsible for the staining pattern of poor absorption followed by high retention. The most common staining technique used to identify acid-fast bacteria is the Ziehl-Neelsen stain or acid-fast stain, in which the acid-fast bacilli are stained bright-red and stand out clearly against a blue background. L-form bacteria are strains of bacteria that lack cell walls. The main pathogenic bacteria in this class is Mycoplasma (not to be confused with Mycobacteria).

Question: What is the most typical staining technique used to identify acid-fast bacteria?


Answer: staining pattern of poor absorption followed by high retention.

Question: What is mycolic acid is responsible for in Mycobacteria?


Answer: high mycolic acid content

Question: What helps Mycobacteria be resistant to decolorization?


Answer: Mycoplasma

Question: What is the main pathogenic bacteria in L-form class ?


Answer: fine filaments of protein

Context: Fimbriae (sometimes called "attachment pili") are fine filaments of protein, usually 2–10 nanometres in diameter and up to several micrometers in length. They are distributed over the surface of the cell, and resemble fine hairs when seen under the electron microscope. Fimbriae are believed to be involved in attachment to solid surfaces or to other cells, and are essential for the virulence of some bacterial pathogens. Pili (sing. pilus) are cellular appendages, slightly larger than fimbriae, that can transfer genetic material between bacterial cells in a process called conjugation where they are called conjugation pili or "sex pili" (see bacterial genetics, below). They can also generate movement where they are called type IV pili (see movement, below).

Question: What are fimbriae?


Answer: involved in attachment to solid surfaces or to other cells

Question: What are fimbriae liable for?


Answer: 2–10 nanometres

Question: What is the diameter of fimbriae?


Answer: cellular appendages

Question: What are pili?


Answer: endospores

Context: Certain genera of Gram-positive bacteria, such as Bacillus, Clostridium, Sporohalobacter, Anaerobacter, and Heliobacterium, can form highly resistant, dormant structures called endospores. In almost all cases, one endospore is formed and this is not a reproductive process, although Anaerobacter can make up to seven endospores in a single cell. Endospores have a central core of cytoplasm containing DNA and ribosomes surrounded by a cortex layer and protected by an impermeable and rigid coat. Dipicolinic acid is a chemical compound that composes 5% to 15% of the dry weight of bacterial spores. It is implicated as responsible for the heat resistance of the endospore.

Question: What are highly resistant dormant structures of certain gram-positive bacteria called?


Answer: is not a reproductive process

Question: Is creating endospore a reproductive process?


Answer: cortex layer

Question: What are ribosomes in endospores are enclosed in?


Answer: Dipicolinic acid

Question: What chemical compound comprises 5% to 15% of the dry weight of bacterial spores?


Answer: show no detectable metabolism

Context: Endospores show no detectable metabolism and can survive extreme physical and chemical stresses, such as high levels of UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure, and desiccation. In this dormant state, these organisms may remain viable for millions of years, and endospores even allow bacteria to survive exposure to the vacuum and radiation in space. According to scientist Dr. Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth — and we know they're very hardened to radiation." Endospore-forming bacteria can also cause disease: for example, anthrax can be contracted by the inhalation of Bacillus anthracis endospores, and contamination of deep puncture wounds with Clostridium tetani endospores causes tetanus.

Question: Is there a metabolism in endospores?


Answer: UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure

Question: What extreme physical and chemical stresses can endospores endure?


Answer: for millions of years

Question: How long can endospores of bacteria stay alive in dormant state?


Answer: Clostridium tetani

Question: What endospore-forming bacteria can cause tetanus disease?


Answer: The distribution of metabolic traits

Context: Bacteria exhibit an extremely wide variety of metabolic types. The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy, but these traits often do not correspond with modern genetic classifications. Bacterial metabolism is classified into nutritional groups on the basis of three major criteria: the kind of energy used for growth, the source of carbon, and the electron donors used for growth. An additional criterion of respiratory microorganisms are the electron acceptors used for aerobic or anaerobic respiration.

Question: What is commonly used to determine taxonomy of bacteria?


Answer: nutritional groups

Question: How is bacterial metabolism determined?


Answer: aerobic or anaerobic respiration

Question: What are electron acceptors accountable for?


Answer: the kind of energy used for growth, the source of carbon, and the electron donors

Question: What are three main criterias of bacterial metabolism?


Answer: organic carbon compounds are used as carbon sources

Context: Carbon metabolism in bacteria is either heterotrophic, where organic carbon compounds are used as carbon sources, or autotrophic, meaning that cellular carbon is obtained by fixing carbon dioxide. Heterotrophic bacteria include parasitic types. Typical autotrophic bacteria are phototrophic cyanobacteria, green sulfur-bacteria and some purple bacteria, but also many chemolithotrophic species, such as nitrifying or sulfur-oxidising bacteria. Energy metabolism of bacteria is either based on phototrophy, the use of light through photosynthesis, or based on chemotrophy, the use of chemical substances for energy, which are mostly oxidised at the expense of oxygen or alternative electron acceptors (aerobic/anaerobic respiration).

Question: How does heterotrophic carbon metabolism occur?


Answer: cellular carbon is obtained by fixing carbon dioxide

Question: When carbon metabolism is called autotrophic?


Answer: Heterotrophic bacteria

Question: What category do parasitic bacteria fall into?


Answer: autotrophic bacteria

Question: Green sulfur-bacteria is typical representative of what type of bacteria?


Answer: the use of chemical substances for energy

Question: What is chemotrophy ?


Answer: inorganic electron donors

Context: Bacteria are further divided into lithotrophs that use inorganic electron donors and organotrophs that use organic compounds as electron donors. Chemotrophic organisms use the respective electron donors for energy conservation (by aerobic/anaerobic respiration or fermentation) and biosynthetic reactions (e.g., carbon dioxide fixation), whereas phototrophic organisms use them only for biosynthetic purposes. Respiratory organisms use chemical compounds as a source of energy by taking electrons from the reduced substrate and transferring them to a terminal electron acceptor in a redox reaction. This reaction releases energy that can be used to synthesise ATP and drive metabolism. In aerobic organisms, oxygen is used as the electron acceptor. In anaerobic organisms other inorganic compounds, such as nitrate, sulfate or carbon dioxide are used as electron acceptors. This leads to the ecologically important processes of denitrification, sulfate reduction, and acetogenesis, respectively.

Question: What do lithotrophs use ?


Answer: organic compounds

Question: What type of electron donors organotrophs use?


Answer: anaerobic organisms

Question: In what organisms is oxygen used as eelectron acceptor?


Answer: chemical compounds

Question: What do respiratory organisms use as electron donors?


Answer: the production of the highly toxic forms of mercury

Context: These processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and dimethylmercury) in the environment. Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves.

Question: What is sulfate-reducing bacteria accountable for?


Answer: ethanol

Question: What is the by-product of non-repiratory anaerobes?


Answer: can switch between fermentation and different terminal electron acceptors

Question: How can anaerobes adjust to the surrounding environment?


Answer: Common inorganic electron donors

Context: Lithotrophic bacteria can use inorganic compounds as a source of energy. Common inorganic electron donors are hydrogen, carbon monoxide, ammonia (leading to nitrification), ferrous iron and other reduced metal ions, and several reduced sulfur compounds. In unusual circumstances, the gas methane can be used by methanotrophic bacteria as both a source of electrons and a substrate for carbon anabolism. In both aerobic phototrophy and chemolithotrophy, oxygen is used as a terminal electron acceptor, whereas under anaerobic conditions inorganic compounds are used instead. Most lithotrophic organisms are autotrophic, whereas organotrophic organisms are heterotrophic.

Question: What are hydrogen and carbon monoxide for Lithotrophic bacteria?


Answer: both a source of electrons and a substrate for carbon anabolism

Question: How can gas methane be used in exceptional set of conditions by methanotrophic bacteria?


Answer: oxygen

Question: What is the main element for aerobic photorophy?


Answer: diffusion

Context: Regardless of the type of metabolic process they employ, the majority of bacteria are able to take in raw materials only in the form of relatively small molecules, which enter the cell by diffusion or through molecular channels in cell membranes. The Planctomycetes are the exception (as they are in possessing membranes around their nuclear material). It has recently been shown that Gemmata obscuriglobus is able to take in large molecules via a process that in some ways resembles endocytosis, the process used by eukaryotic cells to engulf external items.

Question: What chemical process helps bacteria to absorb raw materials?


Answer: in the form of relatively small molecules

Question: How can bacteria obtain raw materials from the environment?


Answer: endocytosis

Question: What process is used by eukaryotic cells to absorb external items?


Answer: molecular channels in cell membranes

Question: What part of bacteria cell is used during diffusion?


Answer: Bacteria grow to a fixed size and then reproduce

Context: Unlike in multicellular organisms, increases in cell size (cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Myxobacteria and aerial hyphae formation by Streptomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.

Question: How size and reproduction are linked in bacteria?


Answer: through binary fission

Question: How does bacteria reproduce?


Answer: divide extremely rapidly

Question: If the conditions are right how long does it take for bacteria to reproduce?


Answer: two identical clone daughter cells

Question: What are produced in cell division?


Answer: solid or liquid media

Context: In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media, such as agar plates, are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.

Question: In what environment are bacteria being cultivated in labs?


Answer: agar plates

Question: What is typical solid setting?


Answer: The use of selective media

Question: What can help to indentify specific bacteria?


Answer: agar plates

Question: Which environment is better to isolate a single example of bacteria strain?


Answer: liquid growth media

Question: Which media is preffered to grow larger volumes of bacteria?


Answer: high levels of nutrients

Context: Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and cyanobacterial) blooms that often occur in lakes during the summer. Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomyces that inhibit the growth of competing microorganisms. In nature, many organisms live in communities (e.g., biofilms) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential for growth of a particular organism or group of organisms (syntrophy).

Question: What is the simple way of producing large volume of bacteria cells?


Answer: nutrients are limited

Question: What caused the evolution of different growth strategies in bacteria?


Answer: biofilms

Question: What can create a subsequent increase of nutrients in natural environment?


Answer: grow extremely rapidly

Question: What do algal bacteria if nutrients are available?


Answer: lag phase

Context: Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport. The final phase is the death phase where the bacteria run out of nutrients and die.

Question: What is the first stage of bacteria adaptation?


Answer: rapid exponential growth

Question: What is the second phase of bacteria growth known for?


Answer: nutrients

Question: The absence of what causes the last stage of bacteria growth?


Answer: stationary phase

Question: What is called the third statge of growth of bacteria?


Answer: four phases

Question: How many phase are in the growth of bacteria?


Answer: circular chromosome

Context: Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacteria Candidatus Carsonella ruddii, to 12,200,000 base pairs in the soil-dwelling bacteria Sorangium cellulosum. Spirochaetes of the genus Borrelia are a notable exception to this arrangement, with bacteria such as Borrelia burgdorferi, the cause of Lyme disease, containing a single linear chromosome. The genes in bacterial genomes are usually a single continuous stretch of DNA and although several different types of introns do exist in bacteria, these are much rarer than in eukaryotes.

Question: What shape is chromosome of bacteria?


Answer: Spirochaetes of the genus Borrelia

Question: What bacteria is an exception to single circular chromosome rule?


Answer: Borrelia burgdorferi

Question: What bacteria is responsible for Lyme disease?


Answer: single linear chromosome

Question: How does chromosome of Borrelia burgdoferi look like?


Answer: inherit identical copies of their parent's genes

Context: Bacteria, as asexual organisms, inherit identical copies of their parent's genes (i.e., they are clonal). However, all bacteria can evolve by selection on changes to their genetic material DNA caused by genetic recombination or mutations. Mutations come from errors made during the replication of DNA or from exposure to mutagens. Mutation rates vary widely among different species of bacteria and even among different clones of a single species of bacteria. Genetic changes in bacterial genomes come from either random mutation during replication or "stress-directed mutation", where genes involved in a particular growth-limiting process have an increased mutation rate.

Question: What makes bacteria an asexual organism?


Answer: changes to their genetic material DNA

Question: What can cause mutation in bacteria?


Answer: random mutation during replication or "stress-directed mutation"

Question: What are two ways changes to DNA of bacteria can occur?


Answer: Transduction of bacterial genes

Context: Transduction of bacterial genes by bacteriophage appears to be a consequence of infrequent errors during intracellular assembly of virus particles, rather than a bacterial adaptation. Conjugation, in the much-studied E. coli system is determined by plasmid genes, and is an adaptation for transferring copies of the plasmid from one bacterial host to another. It is seldom that a conjugative plasmid integrates into the host bacterial chromosome, and subsequently transfers part of the host bacterial DNA to another bacterium. Plasmid-mediated transfer of host bacterial DNA also appears to be an accidental process rather than a bacterial adaptation.

Question: What is the aftermath of infrequent errors during intracellular assembly of virus particles?


Answer: Conjugation

Question: What is the result of bacterial adaptation of E.coli bacteria host and plasmid of another bacteria?


Answer: conjugative plasmid integrates into the host bacterial chromosome

Question: How does conjugation take place?


Answer: It is seldom

Question: Is conjugation a common bacterial adaptation?


Answer: numerous bacterial gene products

Context: Transformation, unlike transduction or conjugation, depends on numerous bacterial gene products that specifically interact to perform this complex process, and thus transformation is clearly a bacterial adaptation for DNA transfer. In order for a bacterium to bind, take up and recombine donor DNA into its own chromosome, it must first enter a special physiological state termed competence (see Natural competence). In Bacillus subtilis, about 40 genes are required for the development of competence. The length of DNA transferred during B. subtilis transformation can be between a third of a chromosome up to the whole chromosome. Transformation appears to be common among bacterial species, and thus far at least 60 species are known to have the natural ability to become competent for transformation. The development of competence in nature is usually associated with stressful environmental conditions, and seems to be an adaptation for facilitating repair of DNA damage in recipient cells.

Question: What does transformation of bacteria depends on?


Answer: this complex process

Question: How simple is the process of transformation?


Answer: enter a special physiological state termed competence

Question: What is the first requirement in order for bacteria to bind and recombine with other bacteria's DNA


Answer: between a third of a chromosome up to the whole chromosome

Question: How big can be the transformation level?


Answer: common

Question: How rare is the transformation among bacteria organisms?


Answer: the same species

Context: In ordinary circumstances, transduction, conjugation, and transformation involve transfer of DNA between individual bacteria of the same species, but occasionally transfer may occur between individuals of different bacterial species and this may have significant consequences, such as the transfer of antibiotic resistance. In such cases, gene acquisition from other bacteria or the environment is called horizontal gene transfer and may be common under natural conditions. Gene transfer is particularly important in antibiotic resistance as it allows the rapid transfer of resistance genes between different pathogens.

Question: Between what species do usually transduction, conjugation and transformation take place?


Answer: transfer of antibiotic resistance

Question: What are the consequences of transfer between different species of bacteria?


Answer: gene acquisition from other bacteria or the environment

Question: What is horizontal gene transfer?


Answer: viruses that infect bacteria

Context: Bacteriophages are viruses that infect bacteria. Many types of bacteriophage exist, some simply infect and lyse their host bacteria, while others insert into the bacterial chromosome. A bacteriophage can contain genes that contribute to its host's phenotype: for example, in the evolution of Escherichia coli O157:H7 and Clostridium botulinum, the toxin genes in an integrated phage converted a harmless ancestral bacterium into a lethal pathogen. Bacteria resist phage infection through restriction modification systems that degrade foreign DNA, and a system that uses CRISPR sequences to retain fragments of the genomes of phage that the bacteria have come into contact with in the past, which allows them to block virus replication through a form of RNA interference. This CRISPR system provides bacteria with acquired immunity to infection.

Question: What are Bacteriophages?


Answer: infect and lyse their host bacteria

Question: What can viruses do to bacteria?


Answer: lethal pathogen

Question: What can happen if Bacteriophage contain genes of host's phenotype?


Answer: CRISPR system provides bacteria with acquired immunity

Question: How can bacteria resist virus DNA?


Answer: single flagellum

Context: Bacterial species differ in the number and arrangement of flagella on their surface; some have a single flagellum (monotrichous), a flagellum at each end (amphitrichous), clusters of flagella at the poles of the cell (lophotrichous), while others have flagella distributed over the entire surface of the cell (peritrichous). The bacterial flagella is the best-understood motility structure in any organism and is made of about 20 proteins, with approximately another 30 proteins required for its regulation and assembly. The flagellum is a rotating structure driven by a reversible motor at the base that uses the electrochemical gradient across the membrane for power. This motor drives the motion of the filament, which acts as a propeller.

Question: What is monotrichous?


Answer: 20 proteins

Question: How many proteins is typical flagellum consist os?


Answer: peritrichous

Question: When flagellum is distributed throughout the surface of the cell?


Answer: amphitrichous

Question: If bacteria has flagellum at each end what is the name of the species?


Answer: uses the electrochemical gradient across the membrane

Question: How does flagellum function within the cell?


Answer: grouping organisms based on similarities

Context: Classification seeks to describe the diversity of bacterial species by naming and grouping organisms based on similarities. Bacteria can be classified on the basis of cell structure, cellular metabolism or on differences in cell components, such as DNA, fatty acids, pigments, antigens and quinones. While these schemes allowed the identification and classification of bacterial strains, it was unclear whether these differences represented variation between distinct species or between strains of the same species. This uncertainty was due to the lack of distinctive structures in most bacteria, as well as lateral gene transfer between unrelated species. Due to lateral gene transfer, some closely related bacteria can have very different morphologies and metabolisms. To overcome this uncertainty, modern bacterial classification emphasizes molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridization, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene. Classification of bacteria is determined by publication in the International Journal of Systematic Bacteriology, and Bergey's Manual of Systematic Bacteriology. The International Committee on Systematic Bacteriology (ICSB) maintains international rules for the naming of bacteria and taxonomic categories and for the ranking of them in the International Code of Nomenclature of Bacteria.

Question: How can we classify the vast variety of bacterial species?


Answer: unclear

Question: Can classification be helpful in determining differences between distinct species?


Answer: lack of distinctive structures in most bacteria,

Question: What supports the uncertainty in classification between the same kind of bacteria?


Answer: different morphologies and metabolisms

Question: What can lateral gene transfer create in bacteria?


Answer: emphasizes molecular systematics

Question: What is the way modern classification tries to determine species?


Answer: all microscopic, single-cell prokaryotes

Context: The term "bacteria" was traditionally applied to all microscopic, single-cell prokaryotes. However, molecular systematics showed prokaryotic life to consist of two separate domains, originally called Eubacteria and Archaebacteria, but now called Bacteria and Archaea that evolved independently from an ancient common ancestor. The archaea and eukaryotes are more closely related to each other than either is to the bacteria. These two domains, along with Eukarya, are the basis of the three-domain system, which is currently the most widely used classification system in microbiolology. However, due to the relatively recent introduction of molecular systematics and a rapid increase in the number of genome sequences that are available, bacterial classification remains a changing and expanding field. For example, a few biologists argue that the Archaea and Eukaryotes evolved from Gram-positive bacteria.

Question: What would original term "bacteria" determine?


Answer: Eubacteria and Archaebacteria

Question: What are two main groups of prokaryotic organisms are divided into?


Answer: archaea and eukaryotes

Question: What groups of organisms are closely related to each other?


Answer: three-domain system

Question: What domain system is commonly used nowdays to classify microorganisms?


Answer: The Gram stain

Context: The Gram stain, developed in 1884 by Hans Christian Gram, characterises bacteria based on the structural characteristics of their cell walls. The thick layers of peptidoglycan in the "Gram-positive" cell wall stain purple, while the thin "Gram-negative" cell wall appears pink. By combining morphology and Gram-staining, most bacteria can be classified as belonging to one of four groups (Gram-positive cocci, Gram-positive bacilli, Gram-negative cocci and Gram-negative bacilli). Some organisms are best identified by stains other than the Gram stain, particularly mycobacteria or Nocardia, which show acid-fastness on Ziehl–Neelsen or similar stains. Other organisms may need to be identified by their growth in special media, or by other techniques, such as serology.

Question: What was developed by Hans Christian Gram?


Answer: 1884

Question: What year was the Grahm stain was developed?


Answer: purple

Question: What color do Gram positive bacteria cell walls turn to after being stained?


Answer: pink

Question: What color is typical for Gram-negative bacteria after staining?


Answer: Ziehl–Neelsen

Question: What stain shows better test results on Norcadia bacteria?


Answer: molecular methods

Context: As with bacterial classification, identification of bacteria is increasingly using molecular methods. Diagnostics using DNA-based tools, such as polymerase chain reaction, are increasingly popular due to their specificity and speed, compared to culture-based methods. These methods also allow the detection and identification of "viable but nonculturable" cells that are metabolically active but non-dividing. However, even using these improved methods, the total number of bacterial species is not known and cannot even be estimated with any certainty. Following present classification, there are a little less than 9,300 known species of prokaryotes, which includes bacteria and archaea; but attempts to estimate the true number of bacterial diversity have ranged from 107 to 109 total species – and even these diverse estimates may be off by many orders of magnitude.

Question: What technique has becoming more popular in classification of bacteria?


Answer: polymerase chain reaction

Question: What tool does DNA based diagnostics use?


Answer: identification of "viable but nonculturable" cells

Question: What else can molecular methods of classification reveal?


Answer: cannot even be estimated with any certainty

Question: Can new methods determine a total number of bacteria species?


Answer: bacteria kill and then consume other microorganisms

Context: Some species of bacteria kill and then consume other microorganisms, these species are called predatory bacteria. These include organisms such as Myxococcus xanthus, which forms swarms of cells that kill and digest any bacteria they encounter. Other bacterial predators either attach to their prey in order to digest them and absorb nutrients, such as Vampirovibrio chlorellavorus, or invade another cell and multiply inside the cytosol, such as Daptobacter. These predatory bacteria are thought to have evolved from saprophages that consumed dead microorganisms, through adaptations that allowed them to entrap and kill other organisms.

Question: Why are certain bacteria called predatory?


Answer: attach to their prey in order to digest them

Question: Which way do Vampirovibrio absorb nutrients of other microorganisms?


Answer: invade another cell and multiply inside the cytosol

Question: What technique do Daptobacter use in order to kill other microorganism?


Answer: saprophages

Question: Where do Daptobacter bacteria come from?


Answer: close spatial associations

Context: Certain bacteria form close spatial associations that are essential for their survival. One such mutualistic association, called interspecies hydrogen transfer, occurs between clusters of anaerobic bacteria that consume organic acids, such as butyric acid or propionic acid, and produce hydrogen, and methanogenic Archaea that consume hydrogen. The bacteria in this association are unable to consume the organic acids as this reaction produces hydrogen that accumulates in their surroundings. Only the intimate association with the hydrogen-consuming Archaea keeps the hydrogen concentration low enough to allow the bacteria to grow.

Question: What helps bacteria to survive?


Answer: anaerobic bacteria

Question: What kind of bacteria can form interspecies hydrogen transfer?


Answer: butyric acid or propionic acid

Question: What do anaerobic bacteria consume?


Answer: rhizosphere

Context: In soil, microorganisms that reside in the rhizosphere (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) carry out nitrogen fixation, converting nitrogen gas to nitrogenous compounds. This serves to provide an easily absorbable form of nitrogen for many plants, which cannot fix nitrogen themselves. Many other bacteria are found as symbionts in humans and other organisms. For example, the presence of over 1,000 bacterial species in the normal human gut flora of the intestines can contribute to gut immunity, synthesise vitamins, such as folic acid, vitamin K and biotin, convert sugars to lactic acid (see Lactobacillus), as well as fermenting complex undigestible carbohydrates. The presence of this gut flora also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion) and these beneficial bacteria are consequently sold as probiotic dietary supplements.

Question: Where do bacteria stay in soil?


Answer: converting nitrogen gas to nitrogenous compounds

Question: What do bacteria do in soil?


Answer: provide an easily absorbable form of nitrogen

Question: How does the conversion help the vegetation?


Answer: over 1,000 bacterial species

Question: What is the amount of bacteria in human intestines?


Answer: through competitive exclusion

Question: How does gut flora prevent growth of pathogenic bacteria?


Answer: bacteria form a parasitic association with other organisms

Context: If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy and tuberculosis. A pathogenic cause for a known medical disease may only be discovered many years after, as was the case with Helicobacter pylori and peptic ulcer disease. Bacterial diseases are also important in agriculture, with bacteria causing leaf spot, fire blight and wilts in plants, as well as Johne's disease, mastitis, salmonella and anthrax in farm animals.

Question: What are the pathogenes?


Answer: may only be discovered many years after

Question: Can cause for most pathogenic diseases be found soon?


Answer: human death and disease

Question: What can pathogenes cause?


Answer: pathogen has a characteristic spectrum of interactions

Context: Each species of pathogen has a characteristic spectrum of interactions with its human hosts. Some organisms, such as Staphylococcus or Streptococcus, can cause skin infections, pneumonia, meningitis and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vasodilation and death. Yet these organisms are also part of the normal human flora and usually exist on the skin or in the nose without causing any disease at all. Other organisms invariably cause disease in humans, such as the Rickettsia, which are obligate intracellular parasites able to grow and reproduce only within the cells of other organisms. One species of Rickettsia causes typhus, while another causes Rocky Mountain spotted fever. Chlamydia, another phylum of obligate intracellular parasites, contains species that can cause pneumonia, or urinary tract infection and may be involved in coronary heart disease. Finally, some species, such as Pseudomonas aeruginosa, Burkholderia cenocepacia, and Mycobacterium avium, are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis.

Question: How pathogenes interact with it's human host?


Answer: exist on the skin or in the nose without causing any disease

Question: Can all bacteria in human body be harmful?


Answer: species of Rickettsia

Question: Which bacteria cause Rocky Mountain spotted fever disiease?


Answer: if they kill bacteria

Context: Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria, or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. An example of how antibiotics produce selective toxicity are chloramphenicol and puromycin, which inhibit the bacterial ribosome, but not the structurally different eukaryotic ribosome. Antibiotics are used both in treating human disease and in intensive farming to promote animal growth, where they may be contributing to the rapid development of antibiotic resistance in bacterial populations. Infections can be prevented by antiseptic measures such as sterilizing the skin prior to piercing it with the needle of a syringe, and by proper care of indwelling catheters. Surgical and dental instruments are also sterilized to prevent contamination by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection.

Question: What type of antibiotics called bacterocidal?


Answer: bacteriostatic

Question: What kind of antibiotics are used for prevention of bacterial growth


Answer: rapid development of antibiotic resistance in bacterial populations

Question: What is the drawback of using antibiotics if agriculture?


Answer: in intensive farming to promote animal growth

Question: Besides in treating human disease where else are antibiotics used?


Answer: sterilizing

Question: What is common prevention method of infections in medicine?


Answer: ability of bacteria to degrade a variety of organic compounds

Context: The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills. Fertilizer was added to some of the beaches in Prince William Sound in an attempt to promote the growth of these naturally occurring bacteria after the 1989 Exxon Valdez oil spill. These efforts were effective on beaches that were not too thickly covered in oil. Bacteria are also used for the bioremediation of industrial toxic wastes. In the chemical industry, bacteria are most important in the production of enantiomerically pure chemicals for use as pharmaceuticals or agrichemicals.

Question: What quality of bacteria is being widely used re-cyling?


Answer: Bacteria

Question: What is being used in cleaning up oil spills?


Answer: used for the bioremediation

Question: What other way is bacteria aiding to nature?


Answer: molecular biology, genetics and biochemistry

Context: Because of their ability to quickly grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics and biochemistry. By making mutations in bacterial DNA and examining the resulting phenotypes, scientists can determine the function of genes, enzymes and metabolic pathways in bacteria, then apply this knowledge to more complex organisms. This aim of understanding the biochemistry of a cell reaches its most complex expression in the synthesis of huge amounts of enzyme kinetic and gene expression data into mathematical models of entire organisms. This is achievable in some well-studied bacteria, with models of Escherichia coli metabolism now being produced and tested. This understanding of bacterial metabolism and genetics allows the use of biotechnology to bioengineer bacteria for the production of therapeutic proteins, such as insulin, growth factors, or antibodies.

Question: What sciences use bacteria?


Answer: 1676

Context: Bacteria were first observed by the Dutch microscopist Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design. He then published his observations in a series of letters to the Royal Society of London. Bacteria were Leeuwenhoek's most remarkable microscopic discovery. They were just at the limit of what his simple lenses could make out and, in one of the most striking hiatuses in the history of science, no one else would see them again for over a century. Only then were his by-then-largely-forgotten observations of bacteria — as opposed to his famous "animalcules" (spermatozoa) — taken seriously.

Question: When was the first time bacteria were observed?


Answer: Dutch microscopist Antonie van Leeuwenhoek

Question: Who discovered bacteria?


Answer: using a single-lens microscope of his own design

Question: How was he able to see bacteria?


Answer: over a century

Question: How long did it take for his discovery to be taken seriously?


Answer: In 1910

Context: Though it was known in the nineteenth century that bacteria are the cause of many diseases, no effective antibacterial treatments were available. In 1910, Paul Ehrlich developed the first antibiotic, by changing dyes that selectively stained Treponema pallidum — the spirochaete that causes syphilis — into compounds that selectively killed the pathogen. Ehrlich had been awarded a 1908 Nobel Prize for his work on immunology, and pioneered the use of stains to detect and identify bacteria, with his work being the basis of the Gram stain and the Ziehl–Neelsen stain.

Question: When was the first antibiotic discovered?


Answer: Paul Ehrlich

Question: Who was the creator of antibiotic?


Answer: Treponema pallidum

Question: What bacteria did he treat first?


Answer: Gram stain and the Ziehl–Neelsen

Question: Who based their research on Enrlich's stains works?


Answer: had been awarded a 1908 Nobel Prize

Question: How was his discovery aknowledged?


Answer: PWB

Context: When the board has no embedded components it is more correctly called a printed wiring board (PWB) or etched wiring board. However, the term printed wiring board has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly (PCA), printed circuit board assembly or PCB assembly (PCBA). The IPC preferred term for assembled boards is circuit card assembly (CCA), and for assembled backplanes it is backplane assemblies. The term PCB is used informally both for bare and assembled boards.

Question: What's the abbreviation for a printed wiring board?


Answer: IPC

Question: What organization likes the term "circuit card assembly" for boards that have already been assembled?


Answer: printed circuit assembly

Question: What would we call a printed circuit board with embedded electronics, abbreviated PCA?


Answer: printed wiring board

Question: What's the more appropriate, but mostly unused, name for a printed circuit board when it doesn't have embedded components?


Answer: CCA

Question: What abbreviation would the IPC use for an assembled circuit board?


Answer: traces

Context: Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. Rub-on dry transfers of common component footprints increased efficiency. Traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout. To fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coating on the blank copper-clad boards.

Question: In the old PCB design method, what was used to connect component pin pads?


Answer: photomask

Question: What did PCB designers used to employ on a mylar sheet?


Answer: self-adhesive tape

Question: What were traces originally made out of?


Answer: common component footprints

Question: Designers would rub on a dry transfer of what to make the process of laying out components simpler?


Answer: copper

Question: What kind of metal coated the blank boards used to make PCBs?


Answer: Panelization

Context: Panelization is a procedure whereby a number of PCBs are grouped for manufacturing onto a larger board - the panel. Usually a panel consists of a single design but sometimes multiple designs are mixed on a single panel. There are two types of panels: assembly panels - often called arrays - and bare board manufacturing panels. The assemblers often mount components on panels rather than single PCBs because this is efficient. The bare board manufactures always uses panels, not only for efficiency, but because of the requirements the plating process. Thus a manufacturing panel can consist of a grouping of individual PCBs or of arrays, depending on what must be delivered.

Question: What process groups PCBs before transfer to a panel?


Answer: a single design

Question: Is it more common for panels to have a single design or many designs?


Answer: assembly panels

Question: What type of panels can also be referred to as an "array?'


Answer: the plating process

Question: What step of the bare board manufacture would be impossible if panels weren't always used?


Answer: bare board manufacturing panels

Question: Besides assembly panels, what's the other type of panel?


Answer: depaneling

Context: The panel is eventually broken apart into individual PCBs; this is called depaneling. Separating the individual PCBs is frequently aided by drilling or routing perforations along the boundaries of the individual circuits, much like a sheet of postage stamps. Another method, which takes less space, is to cut V-shaped grooves across the full dimension of the panel. The individual PCBs can then be broken apart along this line of weakness. Today depaneling is often done by lasers which cut the board with no contact. Laser panelization reduces stress on the fragile circuits.

Question: What is the process called whereby the individual PCBs are separated?


Answer: individual circuits

Question: What boundaries would you follow to separate PCBs on a panel?


Answer: lasers

Question: What technology has made depaneling possible without needing to physically interact with the board?


Answer: space

Question: What does the V-shaped groove method save?


Answer: circuits

Question: What delicate component is less likely to be damaged if laser depanelization is used?


Answer: additive

Context: Subtractive methods remove copper from an entirely copper-coated board to leave only the desired copper pattern. In additive methods the pattern is electroplated onto a bare substrate using a complex process. The advantage of the additive method is that less material is needed and less waste is produced. In the full additive process the bare laminate is covered with a photosensitive film which is imaged (exposed to light through a mask and then developed which removes the unexposed film). The exposed areas are sensitized in a chemical bath, usually containing palladium and similar to that used for through hole plating which makes the exposed area capable of bonding metal ions. The laminate is then plated with copper in the sensitized areas. When the mask is stripped, the PCB is finished.

Question: Do additive or subtractive methods use less raw materials?


Answer: mask

Question: What object is used to expose selected parts of the photosensitive film to light?


Answer: palladium

Question: What chemical element is often present in the bath used to sensitive exposed film after it's been imaged?


Answer: copper

Question: In subtractive methods, what metal covers the board and is then partially removed?


Answer: sensitized areas

Question: In the additive method, which parts of the laminate are plated with copper?


Answer: traces

Context: Semi-additive is the most common process: The unpatterned board has a thin layer of copper already on it. A reverse mask is then applied. (Unlike a subtractive process mask, this mask exposes those parts of the substrate that will eventually become the traces.) Additional copper is then plated onto the board in the unmasked areas; copper may be plated to any desired weight. Tin-lead or other surface platings are then applied. The mask is stripped away and a brief etching step removes the now-exposed bare original copper laminate from the board, isolating the individual traces. Some single-sided boards which have plated-through holes are made in this way. General Electric made consumer radio sets in the late 1960s using additive boards.

Question: In the semi-additive process, what do the areas exposed by the mask become at the end?


Answer: copper

Question: What metal is used to plate the unmasked parts of the board in the semi-additive method?


Answer: etching

Question: After the mask comes off of the board, what step takes off the original plating?


Answer: General Electric

Question: What company used to make radios with additive boards in the mid-20th century?


Answer: any

Question: What weight of plating is possible with copper?


Answer: hobbyists

Context: The simplest method, used for small-scale production and often by hobbyists, is immersion etching, in which the board is submerged in etching solution such as ferric chloride. Compared with methods used for mass production, the etching time is long. Heat and agitation can be applied to the bath to speed the etching rate. In bubble etching, air is passed through the etchant bath to agitate the solution and speed up etching. Splash etching uses a motor-driven paddle to splash boards with etchant; the process has become commercially obsolete since it is not as fast as spray etching. In spray etching, the etchant solution is distributed over the boards by nozzles, and recirculated by pumps. Adjustment of the nozzle pattern, flow rate, temperature, and etchant composition gives predictable control of etching rates and high production rates.

Question: What non-professionals might use immersion etching, since it's the easiest way to make a PCB?


Answer: Heat

Question: If you wanted to speed up the etching process, you could agitate the bath up or add what to it?


Answer: long

Question: Is the immersion etching process long or short compared to other production methods?


Answer: bubble etching

Question: What funny name is used for the etching process where air is blown through the etching solution to get it moving around?


Answer: spray etching

Question: What's the fastest and most easily controlled process for etching?


Answer: four

Context: Multi-layer printed circuit boards have trace layers inside the board. This is achieved by laminating a stack of materials in a press by applying pressure and heat for a period of time. This results in an inseparable one piece product. For example, a four-layer PCB can be fabricated by starting from a two-sided copper-clad laminate, etch the circuitry on both sides, then laminate to the top and bottom pre-preg and copper foil. It is then drilled, plated, and etched again to get traces on top and bottom layers.

Question: If you started with a two-sided laminate etched on either side, laminated to the top and bottom, and processed it again to get traces on the outside layers, how many layers would your final PCB have?


Answer: trace layers

Question: What makes up the inside of a multi-layer PCB?


Answer: heat

Question: Pressure is one thing you need to apply to make a multi-layer PCB; what's the other thing?


Answer: press

Question: What tool is used to push the trace layers in a multi-layer PCB together?


Answer: high-speed-steel

Context: Holes through a PCB are typically drilled with small-diameter drill bits made of solid coated tungsten carbide. Coated tungsten carbide is recommended since many board materials are very abrasive and drilling must be high RPM and high feed to be cost effective. Drill bits must also remain sharp so as not to mar or tear the traces. Drilling with high-speed-steel is simply not feasible since the drill bits will dull quickly and thus tear the copper and ruin the boards. The drilling is performed by automated drilling machines with placement controlled by a drill tape or drill file. These computer-generated files are also called numerically controlled drill (NCD) files or "Excellon files". The drill file describes the location and size of each drilled hole.

Question: What kind of material sometimes used for drilling will lose sharpness quickly if used for PCBs?


Answer: abrasive

Question: What property do PCBs have that makes them tough to drill through?


Answer: coated tungsten carbide

Question: What kind of drill bit do you need to drill holes in a PCB?


Answer: Excellon files

Question: What's another name for NCD files that has an "x" in it?


Answer: numerically controlled drill

Question: What does the "NCD" in "NCD files" mean?


Answer: conductive

Context: The hole walls for boards with two or more layers can be made conductive and then electroplated with copper to form plated-through holes. These holes electrically connect the conducting layers of the PCB. For multi-layer boards, those with three layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by plasma-etch. The de-smear process ensures that a good connection is made to the copper layers when the hole is plated through. On high reliability boards a process called etch-back is performed chemically with a potassium permanganate based etchant or plasma. The etch-back removes resin and the glass fibers so that the copper layers extend into the hole and as the hole is plated become integral with the deposited copper.

Question: What do the hole walls in two-layer PCBs have to be before they can be electroplated?


Answer: three

Question: What's the minimum number of layers a PCB can have to be considered "multi-layer"?


Answer: de-smear

Question: What process does a multi-layer PCB usually undergo before plating to make sure the layers have good connectivity with each other?


Answer: high reliability

Question: What type of boards undergo the etch-back process?


Answer: resin

Question: Etch-back removes glass fibers and what other material?


Answer: oxidizes

Context: Matte solder is usually fused to provide a better bonding surface or stripped to bare copper. Treatments, such as benzimidazolethiol, prevent surface oxidation of bare copper. The places to which components will be mounted are typically plated, because untreated bare copper oxidizes quickly, and therefore is not readily solderable. Traditionally, any exposed copper was coated with solder by hot air solder levelling (HASL). The HASL finish prevents oxidation from the underlying copper, thereby guaranteeing a solderable surface. This solder was a tin-lead alloy, however new solder compounds are now used to achieve compliance with the RoHS directive in the EU and US, which restricts the use of lead. One of these lead-free compounds is SN100CL, made up of 99.3% tin, 0.7% copper, 0.05% nickel, and a nominal of 60ppm germanium.

Question: What happens to untreated copper that makes it difficult to solder?


Answer: benzimidazolethiol

Question: What chemical treatment will prevent bare copper from oxidizing?


Answer: hot air solder levelling

Question: What's the process by which bare copper gets covered in solder?


Answer: solderable surface

Question: What does hot air solder leveling ensure the coated copper will have?


Answer: tin-lead

Question: What alloy can no longer be used in HASL because of restrictions on the use of one of its metal components?


Answer: organic surface protectant

Context: Other platings used are OSP (organic surface protectant), immersion silver (IAg), immersion tin, electroless nickel with immersion gold coating (ENIG), electroless nickel electroless palladium immersion gold (ENEPIG) and direct gold plating (over nickel). Edge connectors, placed along one edge of some boards, are often nickel plated then gold plated. Another coating consideration is rapid diffusion of coating metal into Tin solder. Tin forms intermetallics such as Cu5Sn6 and Ag3Cu that dissolve into the Tin liquidus or solidus(@50C), stripping surface coating or leaving voids.

Question: What does OSP stand for?


Answer: nickel

Question: What metal is often under the gold plating on edge connectors?


Answer: IAg

Question: What's the abbreviation for immersion silver plating?


Answer: Cu5Sn6

Question: Ag3Cu is one intermetallic that tin forms; what's the other one?


Answer: voids

Question: What might the rapid diffusion of coating metal into tin solder leave in the surface coating?


Answer: Electrochemical migration

Context: Electrochemical migration (ECM) is the growth of conductive metal filaments on or in a printed circuit board (PCB) under the influence of a DC voltage bias. Silver, zinc, and aluminum are known to grow whiskers under the influence of an electric field. Silver also grows conducting surface paths in the presence of halide and other ions, making it a poor choice for electronics use. Tin will grow "whiskers" due to tension in the plated surface. Tin-Lead or solder plating also grows whiskers, only reduced by the percentage Tin replaced. Reflow to melt solder or tin plate to relieve surface stress lowers whisker incidence. Another coating issue is tin pest, the transformation of tin to a powdery allotrope at low temperature.

Question: What's the process whereby metal filaments are grown on or in a PCB via DC voltage?


Answer: zinc

Question: Along with silver and aluminum, what metal grows metal filaments when exposed to an electric field?


Answer: conducting surface paths

Question: In addition to "whiskers," what does silver sprout around ions like halide?


Answer: tin pest

Question: What do scientist call the function whereby tin changes when it's very cold?


Answer: tension

Question: What's present in plated surfaces that causes tin to grow metal filaments?


Answer: solder resist

Context: Areas that should not be soldered may be covered with solder resist (solder mask). One of the most common solder resists used today is called "LPI" (liquid photoimageable solder mask). A photo-sensitive coating is applied to the surface of the PWB, then exposed to light through the solder mask image film, and finally developed where the unexposed areas are washed away. Dry film solder mask is similar to the dry film used to image the PWB for plating or etching. After being laminated to the PWB surface it is imaged and develop as LPI. Once common but no longer commonly used because of its low accuracy and resolution is to screen print epoxy ink. Solder resist also provides protection from the environment.

Question: If part of a PCB isn't solderable, what can be used instead?


Answer: solder mask

Question: What's another term used for "solder resist"?


Answer: liquid photoimageable solder mask

Question: What solder resist with a four-word name is a popular choice in the industry?


Answer: photo-sensitive

Question: What kind of coating gets applied to the PWB before light exposure?


Answer: screen print epoxy ink

Question: What solder resist is so inaccurate that few choose it anymore?


Answer: "shorts"

Context: Unpopulated boards are usually bare-board tested for "shorts" and "opens". A short is a connection between two points that should not be connected. An open is a missing connection between points that should be connected. For high-volume production a fixture or a rigid needle adapter is used to make contact with copper lands on the board. Building the adapter is a significant fixed cost and is only economical for high-volume or high-value production. For small or medium volume production flying probe testers are used where test probes are moved over the board by an XY drive to make contact with the copper lands. The CAM system instructs the electrical tester to apply a voltage to each contact point as required and to check that this voltage appears on the appropriate contact points and only on these.

Question: What are bare-board tests looking for besides "opens"?


Answer: copper

Question: What conductive metal are the lands on a circuit board made out of?


Answer: An open

Question: What's an absent connection that needs to be linked up on an unpopulated board called?


Answer: voltage

Question: What does a flying probe tester deliver to the contact points during testing?


Answer: CAM system

Question: What system tells the flying probe where to go and what to do?


Answer: through-hole

Context: Often, through-hole and surface-mount construction must be combined in a single assembly because some required components are available only in surface-mount packages, while others are available only in through-hole packages. Another reason to use both methods is that through-hole mounting can provide needed strength for components likely to endure physical stress, while components that are expected to go untouched will take up less space using surface-mount techniques. For further comparison, see the SMT page.

Question: Surface-mount is one type of construction used in PCB assembly; what's the other one?


Answer: through-hole

Question: Which type of construction makes components that use more space?


Answer: surface-mount

Question: Which of the two kinds of construction is weaker under strain?


Answer: surface-mount

Question: If you're building a circuit board that has a lot of components that won't be used, which construction would be better?


Answer: Joint Test Action Group

Context: In boundary scan testing, test circuits integrated into various ICs on the board form temporary connections between the PCB traces to test that the ICs are mounted correctly. Boundary scan testing requires that all the ICs to be tested use a standard test configuration procedure, the most common one being the Joint Test Action Group (JTAG) standard. The JTAG test architecture provides a means to test interconnects between integrated circuits on a board without using physical test probes. JTAG tool vendors provide various types of stimulus and sophisticated algorithms, not only to detect the failing nets, but also to isolate the faults to specific nets, devices, and pins.

Question: What's the most frequently used test configuration procedure for ICs?


Answer: temporary

Question: Do test circuits create permanent or temporary connections between traces?


Answer: ICs

Question: What component of the printed circuit board is appraised with boundary scan testing?


Answer: JTAG tool vendors

Question: To whom would you go to acquire the algorithms you'd use for the Joint Test Action Group procedures?


Answer: physical test probes

Question: What would you avoid by using the Joint Test Action Group standard?


Answer: conformal coating

Context: PCBs intended for extreme environments often have a conformal coating, which is applied by dipping or spraying after the components have been soldered. The coat prevents corrosion and leakage currents or shorting due to condensation. The earliest conformal coats were wax; modern conformal coats are usually dips of dilute solutions of silicone rubber, polyurethane, acrylic, or epoxy. Another technique for applying a conformal coating is for plastic to be sputtered onto the PCB in a vacuum chamber. The chief disadvantage of conformal coatings is that servicing of the board is rendered extremely difficult.

Question: If a PCB is intended for use in an setting with extreme conditions, what would probably be applied?


Answer: corrosion

Question: The conformal coating can prevent leaking, shorts, and what other type of moisture damage?


Answer: dipping

Question: A conformal coating can be applied by spraying the PCB or by doing what else to it?


Answer: wax

Question: What material was first used for conformal coating?


Answer: servicing

Question: What action is made much more difficult for boards that have a conformal coating?


Answer: antistatic bags

Context: Many assembled PCBs are static sensitive, and therefore must be placed in antistatic bags during transport. When handling these boards, the user must be grounded (earthed). Improper handling techniques might transmit an accumulated static charge through the board, damaging or destroying components. Even bare boards are sometimes static sensitive. Traces have become so fine that it's quite possible to blow an etch off the board (or change its characteristics) with a static charge. This is especially true on non-traditional PCBs such as MCMs and microwave PCBs.

Question: What special protection are most PCBs shipped in?


Answer: static charge

Question: What force can easily change or even completely destroy an etch on a PCB?


Answer: earthed

Question: What's another term for "grounded" in the context of PCBs?


Answer: MCMs

Question: Non-traditional PCBs include microwave PCBs and what other type of board?


Answer: non-traditional

Question: What class of PCBs are even more susceptible to static than standard ones?


Answer: wave soldering machine

Context: The first PCBs used through-hole technology, mounting electronic components by leads inserted through holes on one side of the board and soldered onto copper traces on the other side. Boards may be single-sided, with an unplated component side, or more compact double-sided boards, with components soldered on both sides. Horizontal installation of through-hole parts with two axial leads (such as resistors, capacitors, and diodes) is done by bending the leads 90 degrees in the same direction, inserting the part in the board (often bending leads located on the back of the board in opposite directions to improve the part's mechanical strength), soldering the leads, and trimming off the ends. Leads may be soldered either manually or by a wave soldering machine.

Question: If a lead wasn't soldered manually, what device was used?


Answer: through-hole

Question: Which type of PCB construction technique was used first?


Answer: copper traces

Question: In through-hole construction, what are the leads on the front attached to on the back?


Answer: 90 degrees

Question: For boards with two sides, to what angle are leads bent to in order to install them horizontally?


Answer: mechanical strength

Question: What is improved by bending leads in opposite directions on the back of double-sided PCBs?


Answer: Through-hole

Context: Through-hole manufacture adds to board cost by requiring many holes to be drilled accurately, and limits the available routing area for signal traces on layers immediately below the top layer on multi-layer boards since the holes must pass through all layers to the opposite side. Once surface-mounting came into use, small-sized SMD components were used where possible, with through-hole mounting only of components unsuitably large for surface-mounting due to power requirements or mechanical limitations, or subject to mechanical stress which might damage the PCB.

Question: Which type of construction is more expensive?


Answer: multi-layer

Question: What type of boards end up with limited routing space in through-hole manufacture?


Answer: mechanical stress

Question: What force might damage a PCB if large components are surface mounted?


Answer: small-sized SMD components

Question: What components can be surface mounted to save space?


Answer: power requirements

Question: A component might not be able to be made any smaller because of its mechanical limitations or what other need?


Answer: mid-1990s

Context: Surface-mount technology emerged in the 1960s, gained momentum in the early 1980s and became widely used by the mid-1990s. Components were mechanically redesigned to have small metal tabs or end caps that could be soldered directly onto the PCB surface, instead of wire leads to pass through holes. Components became much smaller and component placement on both sides of the board became more common than with through-hole mounting, allowing much smaller PCB assemblies with much higher circuit densities. Surface mounting lends itself well to a high degree of automation, reducing labor costs and greatly increasing production rates. Components can be supplied mounted on carrier tapes. Surface mount components can be about one-quarter to one-tenth of the size and weight of through-hole components, and passive components much cheaper; prices of semiconductor surface mount devices (SMDs) are determined more by the chip itself than the package, with little price advantage over larger packages. Some wire-ended components, such as 1N4148 small-signal switch diodes, are actually significantly cheaper than SMD equivalents.

Question: When did surface-mount become a commonly used manufacturing process?


Answer: wire leads

Question: What did the new components with end tabs replace?


Answer: automation

Question: What improvement is possible with surface-mounting that enables higher production and lower labor costs?


Answer: surface mount devices

Question: What are SMDs?


Answer: chip

Question: Is it the chip or the package that influences the price of an SMD more?


Answer: etching

Context: Each trace consists of a flat, narrow part of the copper foil that remains after etching. The resistance, determined by width and thickness, of the traces must be sufficiently low for the current the conductor will carry. Power and ground traces may need to be wider than signal traces. In a multi-layer board one entire layer may be mostly solid copper to act as a ground plane for shielding and power return. For microwave circuits, transmission lines can be laid out in the form of stripline and microstrip with carefully controlled dimensions to assure a consistent impedance. In radio-frequency and fast switching circuits the inductance and capacitance of the printed circuit board conductors become significant circuit elements, usually undesired; but they can be used as a deliberate part of the circuit design, obviating the need for additional discrete components.

Question: What process is a trace left over from?


Answer: width

Question: Along with thickness, what determines the resistance of a trace?


Answer: signal

Question: What type of trace is often narrower than a ground trace?


Answer: copper

Question: In a multi-layer board, what metal would a ground plane be mostly made out of?


Answer: microwave circuits

Question: What type of circuits use a stripline and microstrip format?


Answer: type designation

Context: The cloth or fiber material used, resin material, and the cloth to resin ratio determine the laminate's type designation (FR-4, CEM-1, G-10, etc.) and therefore the characteristics of the laminate produced. Important characteristics are the level to which the laminate is fire retardant, the dielectric constant (er), the loss factor (tδ), the tensile strength, the shear strength, the glass transition temperature (Tg), and the Z-axis expansion coefficient (how much the thickness changes with temperature).

Question: What element of a laminate is designated by the cloth to resin ratio, among other things?


Answer: Z-axis expansion coefficient

Question: What's the name for the measurement of a laminate's change in thickness as its temperature changes?


Answer: Tg

Question: What's the abbreviation for the glass transition temperature of a laminate?


Answer: Teflon

Context: There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of the circuit. Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1, CEM-1 or CEM-3. Well known pre-preg materials used in the PCB industry are FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester). Thermal expansion is an important consideration especially with ball grid array (BGA) and naked die technologies, and glass fiber offers the best dimensional stability.

Question: What's the common name of polytetrafluoroethylene?


Answer: phenolic cotton paper

Question: What pre-preg material is designated by "FR-2"?


Answer: ball grid array

Question: To what type of packaging is thermal expansion particularly critical?


Answer: glass fiber

Question: What material delivers optimum dimensional stability?


Answer: FR-6

Question: What dielectric is matte glass and polyester?


Answer: woven

Context: The reinforcement type defines two major classes of materials - woven and non-woven. Woven reinforcements are cheaper, but the high dielectric constant of glass may not be favorable for many higher-frequency applications. The spatially nonhomogeneous structure also introduces local variations in electrical parameters, due to different resin/glass ratio at different areas of the weave pattern. Nonwoven reinforcements, or materials with low or no reinforcement, are more expensive but more suitable for some RF/analog applications.

Question: Along with the non-woven class, what makes up the reinforcement type materials?


Answer: non-woven

Question: Which is the more expensive reinforcement type?


Answer: spatially nonhomogeneous

Question: What type of structure do woven reinforcements have that cause them to have variation in their electrical parameters?


Answer: resin/glass

Question: Which ratio varies because of the structure of woven reinforcements?


Answer: RF/analog

Question: For what kind of applications are non-woven reinforcement materials better than woven ones?


Answer: glass transition temperature

Context: At the glass transition temperature the resin in the composite softens and significantly increases thermal expansion; exceeding Tg then exerts mechanical overload on the board components - e.g. the joints and the vias. Below Tg the thermal expansion of the resin roughly matches copper and glass, above it gets significantly higher. As the reinforcement and copper confine the board along the plane, virtually all volume expansion projects to the thickness and stresses the plated-through holes. Repeated soldering or other exposition to higher temperatures can cause failure of the plating, especially with thicker boards; thick boards therefore require high Tg matrix.

Question: What's the temperature at which resin softens and expands called?


Answer: joints

Question: Along with vias, what makes up the components of a board?


Answer: mechanical overload

Question: What will happen to the components when the temperature of resin goes above that of glass transition?


Answer: high Tg matrix

Question: What do thick boards require to resist plating failure?


Answer: glass

Question: When resin stays below Tg, its thermal expansion is similar to that of copper and what other material?


Answer: Moisture absorption

Context: Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water may be also soaked by capillary forces through voids in the materials and along the reinforcement. Epoxies of the FR-4 materials aren't too susceptible, with absorption of only 0.15%. Teflon has very low absorption of 0.01%. Polyimides and cyanate esters, on the other side, suffer from high water absorption. Absorbed water can lead to significant degradation of key parameters; it impairs tracking resistance, breakdown voltage, and dielectric parameters. Relative dielectric constant of water is about 73, compared to about 4 for common circuitboard materials. Absorbed moisture can also vaporize on heating and cause cracking and delamination, the same effect responsible for "popcorning" damage on wet packaging of electronic parts. Careful baking of the substrates may be required.

Question: What will happen to the materials when a board gets wet or is in a humid area?


Answer: cracking

Question: If materials absorb moisture and then are heated enough to vaporize the water, the board might show delamination or what other type of damage?


Answer: 0.15%

Question: What percentage absorption do F-4 epoxies have?


Answer: 4

Question: What's the approximate relative dielectric constant of most materials in circuit boards?


Answer: Teflon

Question: What material has an absorption rate of only 0.01%?


Answer: three ounces

Context: The printed circuit board industry defines heavy copper as layers exceeding three ounces of copper, or approximately 0.0042 inches (4.2 mils, 105 μm) thick. PCB designers and fabricators often use heavy copper when design and manufacturing circuit boards in order to increase current-carrying capacity as well as resistance to thermal strains. Heavy copper plated vias transfer heat to external heat sinks. IPC 2152 is a standard for determining current-carrying capacity of printed circuit board traces.

Question: What's the minimum amount of copper a layer in a PCB can have to be considered "heavy copper"?


Answer: 0.0042 inches

Question: About how thick would a PCB layer be if it contained three oz. of copper?


Answer: current

Question: What will a circuit board with heavy copper carry very well?


Answer: thermal strains

Question: What would a PCB designer use heavy copper to make their circuit board resist?


Answer: external heat sinks

Question: Where does the heat go when it leaves heavy copper-plated vias?


Answer: routing of wires

Context: Since it was quite easy to stack interconnections (wires) inside the embedding matrix, the approach allowed designers to forget completely about the routing of wires (usually a time-consuming operation of PCB design): Anywhere the designer needs a connection, the machine will draw a wire in straight line from one location/pin to another. This led to very short design times (no complex algorithms to use even for high density designs) as well as reduced crosstalk (which is worse when wires run parallel to each other—which almost never happens in Multiwire), though the cost is too high to compete with cheaper PCB technologies when large quantities are needed.

Question: What arduous aspect of the process can designers skip in Multiwire?


Answer: a connection

Question: What does the machine create by drawing a straight line between two points on the board?


Answer: crosstalk

Question: Along with quick design times, what problem does Multiwire cut down on?


Answer: cost

Question: What makes Multiwire impractical to use when large quantities of a board are needed?


Answer: wires

Question: In simple language, what are the interconnections in an embedding matrix?


Answer: Cordwood

Context: Cordwood construction can save significant space and was often used with wire-ended components in applications where space was at a premium (such as missile guidance and telemetry systems) and in high-speed computers, where short traces were important. In cordwood construction, axial-leaded components were mounted between two parallel planes. The components were either soldered together with jumper wire, or they were connected to other components by thin nickel ribbon welded at right angles onto the component leads. To avoid shorting together different interconnection layers, thin insulating cards were placed between them. Perforations or holes in the cards allowed component leads to project through to the next interconnection layer. One disadvantage of this system was that special nickel-leaded components had to be used to allow the interconnecting welds to be made. Differential thermal expansion of the component could put pressure on the leads of the components and the PCB traces and cause physical damage (as was seen in several modules on the Apollo program). Additionally, components located in the interior are difficult to replace. Some versions of cordwood construction used soldered single-sided PCBs as the interconnection method (as pictured), allowing the use of normal-leaded components.

Question: What type of construction is best for applications that need to portion space carefully?


Answer: axial-leaded components

Question: What gets mounted in the middle of two parallel planes in a cordwood construction?


Answer: nickel-leaded

Question: What type of component has to be used in cordwood construction to its detriment?


Answer: shorting

Question: What do insulating cards prevent between interconnection layers?


Answer: Differential thermal expansion

Question: What force caused the physical damage to components that affected the Apollo program?


Answer: Albert Hanson

Context: Development of the methods used in modern printed circuit boards started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented a print-and-etch method in Britain, and in the United States Max Schoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Ducas in 1927 patented a method of electroplating circuit patterns.

Question: Who was the German inventor who wrote in 1903 about conductors being laminated in layers to a board?


Answer: linen paper

Question: What material did Thomas Edison experiment with by trying to chemically attach conductors to it?


Answer: 1913

Question: What year did Arthur Berry patent his print-and-etch method?


Answer: a patterned mask

Question: In Max Schoop's method, what was used to create the flame-sprayed pattern on the board?


Answer: Charles Ducas

Question: Who obtained a patent in 1927 for his method of electroplating circuit patterns?


Answer: a radio set

Context: The Austrian engineer Paul Eisler invented the printed circuit as part of a radio set while working in England around 1936. Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II. After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army. At around the same time in Britain work along similar lines was carried out by Geoffrey Dummer, then at the RRDE.

Question: What was Paul Eisler making when he came up with the printed circuit?


Answer: World War II

Question: What event prompted the United States to adopt the printed circuit to make proximity fuses?


Answer: 1948

Question: When was the printed circuit released for commercial use in the U.S.?


Answer: Geoffrey Dummer

Question: Who was working on the same type of large-scale application of printed circuits as the U.S. in Britain in the mid-1950s?


Answer: Auto-Sembly

Question: What process was created by the U.S. Army that led to innovation in consumer electronics?


Answer: Globe Union

Context: During World War II, the development of the anti-aircraft proximity fuse required an electronic circuit that could withstand being fired from a gun, and could be produced in quantity. The Centralab Division of Globe Union submitted a proposal which met the requirements: a ceramic plate would be screenprinted with metallic paint for conductors and carbon material for resistors, with ceramic disc capacitors and subminiature vacuum tubes soldered in place. The technique proved viable, and the resulting patent on the process, which was classified by the U.S. Army, was assigned to Globe Union. It was not until 1984 that the Institute of Electrical and Electronics Engineers (IEEE) awarded Mr. Harry W. Rubinstein, the former head of Globe Union's Centralab Division, its coveted Cledo Brunetti Award for early key contributions to the development of printed components and conductors on a common insulating substrate. As well, Mr. Rubinstein was honored in 1984 by his alma mater, the University of Wisconsin-Madison, for his innovations in the technology of printed electronic circuits and the fabrication of capacitors.

Question: What company developed the first electronic circuit that could be mass produced and was durable enough to be fired from a gun?


Answer: Harry W. Rubinstein

Question: Who was in charge of the Centralab Division of Globe Union when the PCB used in anti-aircraft fuses was invented?


Answer: University of Wisconsin-Madison

Question: Where did Harry Rubinstein attend college?


Answer: ceramic

Question: What was the plate used for anti-aircraft proximity fuses in World War II made out of?


Answer: Cledo Brunetti Award

Question: What award did Rubinstein win in 1984 for his contributions?


Answer: through-hole

Context: Originally, every electronic component had wire leads, and the PCB had holes drilled for each wire of each component. The components' leads were then passed through the holes and soldered to the PCB trace. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered. The patent they obtained in 1956 was assigned to the U.S. Army. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are wasteful since drilling holes is expensive and the protruding wires are merely cut off.

Question: What type of construction was originally used for all electronic components?


Answer: 1949

Question: In what year was the Auto-Sembly process created?


Answer: 1956

Question: What year was the patent for the Auto-Sembly process granted?


Answer: U.S. Army

Question: Although two men developed the Auto-Sembly process, to whom was the patent officially granted?


Answer: drilling holes

Question: Which part of the Auto-Sembly manufacturing process is the most costly?