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Brock Biology of Microorganis 15tH ed by. Madigan, Kelly S. Bender, Daniel H. Buckley, W. Matthew Sattley & David A. Stahl
Brock Biology of Microorganisms, 15e (Madigan et al.)
Chapter 3 Microbial Metabolism
3.1 Multiple Choice Questions
1) The prokaryotic transport system that involves a substrate-binding protein, a membrane-integrated transporter, and an ATP-hydrolyzing protein is
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.2
2) The sum of all biosynthetic reactions in a cell is known as
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
3) Based on the functional roles of phosphate in various microbial metabolisms, which of the following compounds most likely contain phosphate?
Answer: C
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.1
4) Which of the following would be used by a chemoorganotroph for energy?
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.3
5) Which of the following statements is FALSE?
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.6
6) All microorganisms require
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
7) Which element functions BOTH as an enzyme cofactor and as a stabilizer of ribosomes and nucleic acids?
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
8) Based on your understanding of metabolism, generalize when an enzymes rate of activity can be changed.
Answer: C
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.5
9) The change in Gibbs free energy for a particular reaction is most useful in determining
Answer: C
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.4
10) Which is an example of a micronutrient?
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
11) Aseptic technique refers to
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 1.9
12) To ensure growth of a newly discovered bacterium with unknown nutritional requirements, it would be best to begin with a ________ medium rather than a ________ medium.
Answer: A
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.2
13) If G0 is negative, the reaction is
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.4
14) Activation energy is the energy
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.5
15) A catalyst
the reaction is completed.
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.5
16) The portion of an enzyme to which substrates bind is referred to as the
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.5
17) What is the difference between a coenzyme and a prosthetic group?
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.5
18) If an oxidation reaction occurs
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.6
19) The class of macromolecules in microorganisms that contributes most to biomass is
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
20) A chemoorganotroph and a chemolithotroph in the same environment would NOT compete for
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.3
21) A chemoorganotroph and a photoautotroph in the same environment would NOT compete for
Answer: D
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.3
22) The Embden-Meyerhof-Parnas pathway is another name for
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
23) The net gain of ATP per molecule of glucose fermented is
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
24) Which of the following is a common energy storage polymer in microorganisms?
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
25) Fermentation has a relatively low ATP yield compared to aerobic respiration because
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
26) From the standpoint of fermentative microorganisms, the crucial product in glycolysis is
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
27) In aerobic respiration, the final electron acceptor is
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.10
28) Which of the following is NOT membrane-associated?
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.10
29) During electron transport reactions
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
30) The rising of bread dough is the result of
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.8
31) Which intermediate compound(s) in the citric acid cycle is/are often used for biosynthetic pathways as well as carbon catabolism?
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.9
32) Microbial growth on the two-carbon acetate substrate invokes
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.9
33) Which is one major difference between anaerobic and aerobic respiration?
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.12
34) For a carbon source, chemoorganotrophs generally use compounds such as
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.3
35) All of the following are non-protein electron carriers EXCEPT
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.10
36) Which two metabolic processes are most dissimilar?
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.13
37) How does the proton motive force lead to production of ATP?
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
38) Five-carbon sugars are used in the
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.13
39) Improperly functioning acyl carrier proteins (ACPs) would likely result in
Answer: D
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.15
40) A bacterium running low on NADPH could ________ to generate more of this coenzyme.
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.13
41) One example of an electron acceptor that can be used in anaerobic respiration is
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.12
42) When culturing a chemoorganoheterophic bacterium, what outcome is LEAST likely to occur if ammonia and phosphate are provided at equal concentrations?
Answer: A
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.3
43) Most of the carbon in amino acid biosynthesis comes from
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.14
44) Which metabolic cycle or pathway is LEAST likely to be invoked during the biosynthesis of DNA?
Answer: C
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.14
45) Hypothetically, if free electrons existed in sufficient numbers for enzymes to use in metabolic reactions
Answer: D
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.11
46) Which metabolic strategy does NOT invoke the proton motive force for energy conservation?
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.12
3.2 True/False Questions
1) ATP-binding cassette transport systems have high substrate affinity and thus help microorganisms survive in low nutrient environments.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.2
2) A bacterial isolate that grows better on a nutrient agar plate supplemented with amino acids but still grows in a nutrient agar plate lacking amino acids suggests amino acids are trace nutrients for the isolate.
Answer: FALSE
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.1
3) Regeneration of oxaloacetate is essential for the citric acid cycle to be cyclical.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.9
4) Depending on the particular metabolism of a bacterium, electron transport can be used to energize and rotate ATP synthase.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
5) Each amino acid made during protein biosynthesis first requires a separate biosynthetic pathway to be invoked by a cell.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.14
6) The terminating step of moving electrons onto oxygen releases additional ATP during aerobic metabolism not made during anaerobic growth.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
7) Nitrogenases not only reduce N2 but also can act on acetylene (C2H2).
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
8) Due to the number of phosphate groups, ATP has approximately three times more energy stored than AMP, and ADP has approximately two-thirds the energy stored of ATP.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.7
9) In a given chemical reaction, if the free energy of formation is known for all of the reactants and each of the products, the change in free energy can be calculated for the reaction.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.4
10) Free-energy calculations are dependent on the rates of the reactions.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.4
11) With respect to nitrogen utilization, relatively few bacteria can use NH3 whereas many more can make use of N2.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.14
12) The proton motive force is most often generated by splitting of H2.
Answer: FALSE
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.11
13) Biosynthesis of glucose can occur by compounds other than sugars via gluconeogenesis.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.13
14) If a substance is reduced, it gains electrons.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.6
15) Molybdenum is a cofactor for nitrogenase, which means every nitrogen-fixing microorganisms will not be able to fix nitrogen without Mo.
Answer: TRUE
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.1
16) Magnesium is not considered a growth factor for microorganisms, because growth factors are always organic compounds.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.1
17) Cells require iron supplemented in their growth medium as a trace metal, because it is consumed by quinones during electron transport for ATP production.
Answer: FALSE
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.10
18) Varied coenzyme availability increases the diversity of enzymatic reactions in both biosynthetic and catabolic pathways possible in a cell.
Answer: TRUE
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.5
19) The energy released from the hydrolysis of coenzyme A is conserved in the synthesis of ATP.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.7
20) In substrate-level phosphorylation, ATP storage is depleted during the steps in catabolism of the fermentable compounds.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
21) Catabolic pathways are essential for microorganisms to obtain energy, because biosynthetic reactions for cellular growth generally require energy input.
Answer: TRUE
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.13
22) In electron transport systems, the electron carriers are membrane associated.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
23) Heme prosthetic groups are involved in electron transfer with quinones.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.5
24) During the electron transport process, protons and electrons become physically separated in the cell membrane.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.10
25) Many defined growth media that support microbial growth lack malonate, which is an important precursor for biosynthesis of lipid membranes. Based on this, we can infer cells also must have a metabolic pathway to generate malonate from other compounds.
Answer: TRUE
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.15
26) The net result of electron transport is the generation of a pH gradient and an electrochemical potential across the membrane.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
27) A bacterium that lacks an arginine biosynthetic pathway would still be able to make proteins with arginine and grow only if arginine is supplemented into the growth medium.
Answer: TRUE
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.14
3.3 Essay Questions
1) Why is energy required for nutrient transport? Give an example of a system that transports nutrients and describe what source of energy is used to move the nutrients into the cell.
Answer: Energy is required for nutrient transport because nutrient concentration outside of the cell is lower than the nutrient concentrations inside the cell, thus nutrient transport moves solutes against a concentration gradient and requires energy. There are three examples in the text. The student could describe any one of them. They are (i) Simple transporter such as lac permease. Each nutrient molecule is cotransported into the cell with a H+ ion, thus the proton motive force provides the energy to transport nutrients. (ii) Group translocation such as sugar phosphotransferases. Each nutrient molecule is modified during the transport process. The modification, in this case, phosphorylation, releases energy, thus the energy source is an energy-rich compound such as phosphoenol pyruvate or some other phosphorylated compound. (iii) ABC transporters. In this example specific binding proteins bind to nutrient molecules with high affinity. Movement of the nutrient into the cell is coupled to ATP hydrolysis, thus ATP is the source of energy for transporting nutrients.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.2
2) Explain the differences between symporters, and antiporters.
Answer: Answers should highlight differences in transport direction and energy input.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.2
3) Compare and contrast defined media and complex media. Use specific examples in your answer.
Answer: Defined media are prepared by adding individual pure chemicals in known quantities. In this way, the medium itself can be explicitly defined. For example, 5 mM NaCl, 3 mM KH2PO4, 1.5 mM NH4Cl, 2.5% glucose, and 3% acetate is a defined medium, because each ingredient added is at a known concentration and the chemicals present are known. Complex media needs only to contain one undefined product to be considered complex or undefined. An example of an undefined medium is 5 mM NaCl, 2.5% tryptone and 2.5% yeast extract, because both tryptone and yeast extract are not individual chemical structures but instead contain an assortment of compounds at unknown (imprecise) quantities.
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.1
4) Categorize the circumstances under which the same substance (molecule) can be either an electron donor or an electron acceptor.
Answer: Answers should explain that not all molecules are strictly one or the other, and each molecule must be compared to the other in a pair to determine which is the electron acceptor and which is an electron donor.
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.6
5) Contrast fermentation and respiration in terms of electron donor, electron acceptor, type of ATP production, and relative number of ATP produced.
Answer: Respiration should be distinguished as using separate electron donors and acceptors (such as organic carbon as the electron donor and oxygen as the electron acceptor), while fermentation splits organic molecules in order to oxidize one part of the molecule and reduce the other part in order to regenerate NAD+. Fermentation uses substrate level phosphorylation to generate relatively few ATP, while respiration uses oxidative phosphorylation to generate more ATP.
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.8
6) Summarize the roles the proton motive force has in microbial metabolism.
Answer: The proton motive force uses an energized cell membrane for ATP synthesis via ATPase, transporting some ions and molecules into and out of the cell, and flagellar rotation.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.11
7) Discuss why energy yield in an organism undergoing anaerobic respiration is less than that of an organism undergoing aerobic respiration.
Answer: One possible explanation could point to the substrate-level phosphorylation process itself as being less energy yielding than (aerobic) oxidative phosphorylation. Another reason is the fate of pyruvate itself, where fermentation is unable to take it through the higher energy yielding process, which requires O2 as a terminal electron acceptor. Other answers could discuss the E0 being greatest with the O2/H2O redox couple in aerobic metabolism compared to anaerobic redox couples.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.12
8) Explain the biosynthetic and bioenergetic roles of the citric acid cycle.
Answer: Some of the molecules generated during the citric acid cycle, such as alpha-ketoglutarate, oxalacetate, and succinyl-CoA, can serve as precursors for the biosynthesis of critical cellular components such as amino acids, chlorophyll, and cytochromes. The bioenergetic component of the cycle should be described in the context of FADH2 and NADH electron donors storing energy potential, usable in electron transport where O2 is reduced to water.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.8
9) In an aquatic microbial community where a photoautotroph, chemoorganoheterotroph, and nitrogen fixing bacterium are present, predict an environmental perturbation that would cause only one to be outcompeted by the other two groups and explain how each group would respond.
Answer: Answers will vary but should highlight a unique feature of one of the groups such as: photoautotrophs are sensitive to photon (light) availability, chemoorganoheterotrophs require organic molecules for carbon, and nitrogen fixing bacteria use N2 gas.
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.3
10) Differentiate between exergonic and endergonic in terms of free-energy calculations.
Answer: A positive change in free energy (G0) means the reaction needs energy input to occur (called endergonic), whereas a negative G0 needs no energy input and actually releases excess energy (called exergonic).
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 3.4
11) Explain what an enzyme must accomplish to catalyze a specific reaction.
Answer: Answers will vary, but the focus of the answer should be on overcoming the required activation energy.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.5
12) A beer-making microbiologist noticed that no matter how long the brewing process went, 3% alcohol was the maximum produced. Hypothesize what is causing this low level of alcohol in reference to the brewers recipe and recommend how a higher alcohol yield could be achieved. Ethanol is toxic at high concentrations, but ignore this factor to focus on microbial metabolism.
Answer: Answers will vary but one explanation is a low substrate concentration resulted in low fermentation to produce ethanol. Providing more carbohydrates such as glucose to the yeast in the recipe for the same growth period would increase fermentation activity and ethanol production. Another explanation is that there may be too much oxygen introduced during the brewing process, which would result in the complete oxidation of glucose instead of fermentation to ethanol. The brewer would need to take more precautions to exclude oxygen during brewing.
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.8
13) Explain why the amount of energy released in a redox reaction depends on the nature of both the electron donor and the electron acceptor.
Answer: Answers should emphasize that energy does not come from specific molecules but rather from the difference in reduction potential between two molecules. For example, assigning arbitrary values and subtracting them from one another by comparing two different electron acceptors to one donor would indicate differences in energy for an electron acceptor. In a similar way, this could also be shown to mathematically explain electron donors having an equal role in determining E0.
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 3.6
14) Consider a pizza dough made by vigorously mixing to form gluten and evenly disperse the ingredients such as bakers yeast (Saccharomyces cerevisiae). Predict the metabolic differences yeast would have in a thinly flattened dough and in a spherical dough ball.
Answer: A flattened dough would have higher surface area and more oxygen exposure to support aerobic respiration of S. cerevisiae. The dough ball on the other hand would initially have aerobic metabolism of S. cerevisiae due to the mixing. Once oxygen is depleted from respiration the yeast would begin anaerobic fermentation, especially in the center of the dough ball while the surface of the dough ball could still support aerobic growth if not enclosed in a container.
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 3.8
Brock Biology of Microorganisms, 15e (Madigan et al.)
Chapter 13 Microbial Evolution and Systematics
13.1 Multiple Choice Questions
1) The earliest stromatolites were probably formed by
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
2) What two gases were most abundant on early Earth?
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
3) Compared with today, the temperature on Earth during its first half-billion years was probably
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
4) The earliest RNA probably functioned in
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
5) Chemical reactions involving ________ have been proposed as energy-yielding reactions for the earliest organisms on Earth.
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
6) Evolution is driven by
Answer: D
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.5
7) Microorganisms were probably restricted to the oceans and subsurface environments until
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
8) Which of the following is an assumption used in the molecular clock approach?
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.5
9) An important molecule in sequence-based evolutionary analyses of microbes are ________ genes.
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.7
10) A monophyletic group is a group that
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.8
11) A gene for a specific trait may have more than one form, allowing the trait to vary. These sequence variants of a gene are called a(n)
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.5
12) A key concept in evolution is that all mutations are
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.5
13) LUCA is
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
14) Horizontal gene transfer
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
15) Molecular sequencing suggests that mitochondria arose from a group of prokaryotic organisms within the
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.4
16) Which statement most closely expresses our present understanding?
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.4
17) Two tubes are inoculated from the same tube containing a bacterial culture. The cultures are then transferred every day for 2 months. All of the media and growth conditions are the same in every tube. After 2 months of cultivation, the fitness and genotype frequencies of the populations in the two tubes are compared. The fitness of the two cultures is the same, but the genotype frequencies are very different in the two cultures. How is this possible?
Answer: D
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 13.5
18) If you allowed 10 identical parallel Salmonella cultures to evolve for 10,000 generations under new growth conditions with very little nitrogen, the parallel cultures would
Answer: C
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 13.5
19) Both deletions and insertions occur during the evolution of microbial genomes. Insertions bring in new genes that may be useful for the cell. Deletions
Answer: A
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.6
20) Polyphasic taxonomy uses methods that include
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.6
21) Ribotyping
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.9
22) Which is NOT a characteristic of a primitive state of microbial evolution?
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.1
23) Because DNA-DNA hybridization reveals subtle differences in genes, it is useful for differentiating organisms from different
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.8
24) Which taxonomic tool would scientists use if they wanted to determine if an outbreak of food poisoning was caused by a particular strain of a pathogen?
Answer: C
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.9
25) It is believed that phototrophy arose approximately 3.3 billion years ago in
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
26) The oxic atmosphere created conditions that led to the evolution of various new metabolic pathways, such as
Answer: D
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.2
27) You are studying 12 new isolates from the human skin. Their average nucleotide identity for shared orthologous genes is 97%.The isolates would most likely be
Answer: A
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 13.8
28) The pan genome of a microbial species is constantly changing because of
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.6
29) Microbial ________ studies the diversity of microorganisms and links their phylogeny with ________.
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.7
30) The earliest photosynthetic microbes, before the cyanobacterial lineage developed, oxidized substances other than water. What was produced by these microbes instead of oxygen?
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
31) Based on the phylogenetic tree below, which of the following statements is FALSE?
Answer: B
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.7
32) The early energy reactions used hydrogen, which is a powerful
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
33) Oxygen did not accumulate in the early atmosphere until it reacted with reduced materials, especially ________, in the oceans.
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
34) As oxygen appeared in the atmosphere, ________ also accumulated, which formed a protective barrier that protects the Earth from ________.
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
35) Two eukaryotic organelles that are hypothesized to be the result of endosymbiosis are the ________ and the ________.
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.4
36) Microbial species have a core genome and a pan genome. What is the difference between the two?
Answer: C
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.6
37) What characteristics make a gene a good candidate for determining the evolutionary relationships between organisms?
Answer: D
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.7
38) Which of the following statements is FALSE concerning the universal tree of life?
Answer: D
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.3
39) ________ formed the semipermeable membrane-like surfaces for the earliest life forms.
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.4
40) The first catalytic and self-replication biological molecule was most likely
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
41) The evolutionary history of a group of organisms is called its ________ and it is inferred from ________.
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
42) One widely used method of examining evolutionary relationships is ________, which is based on the assumption that evolution is most likely to have proceeded by the path requiring fewest changes.
Answer: C
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.7
43) Multilocus sequence typing (MLST) involves sequencing several different
Answer: B
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.9
44) Systematic analysis now commonly includes ________ to identify, characterize, and determine relationships between new strains of bacterial species.
Answer: A
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.9
13.2 True/False Questions
1) The atmosphere of primitive Earth is usually described as an oxidizing atmosphere.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
2) The earliest nucleic acid was probably a simple DNA molecule.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
3) The establishment of DNA as the genome of the cell may have resulted from the need to store genetic information in a more stable form than RNA.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.1
4) Eukaryotes originated after the rise in atmospheric oxygen.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.4
5) A type strain is the first strain of a new species to be identified and described.
Answer: TRUE
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.10
6) Sequencing technology and molecular phylogenetic analyses have had very little impact on our understanding of the evolution and diversity of life on Earth.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.9
7) Molecular phylogeny and rRNA analysis provided the evidence used to separate Bacteria and Archaea into distinct domains.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
8) Organisms with greater phylogenetic distance in their genomes have less gene exchange than those with less phylogenetic distance.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.6
9) Microbial species are difficult to define because they are seldom monophyletic.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.8
10) Organisms within a species should have strong phenotypic cohesiveness.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.8
11) At present there are four phyla in the domain Bacteria.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
12) The universal phylogenetic tree shows that the Bacteria diverged from the Archaea before the Eukarya diverged from the Archaea.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
13) The 16S rRNA gene sequence is an approximately 1,465 bp linear strand of single stranded RNA.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.7
14) DNA-DNA hybridization is a sensitive method for revealing subtle genetic differences because it measures the degree of sequence similarity between two genomes.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.8
15) One phenotypic trait used for species identification and description is the analysis of the types and proportions of the fatty acids present in the cytoplasmic and outer membranes. The methodology employed is often nicknamed FAME.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.9
16) In taxonomy, family is a more general term than order.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.10
17) Oxygen was a driving factor in the formation of eukaryotic cells.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
18) The primary domains were founded based on comparative ribosomal RNA gene sequencing.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
19) All unicellular organisms belong to the same domain of life.
Answer: FALSE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
20) Approximately 3.7 billion years ago Archaea and Bacteria diverged as being distinct from each other.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.3
21) When exposed to UV light, oxygen gas produces ozone gas.
Answer: TRUE
Blooms Taxonomy: 1-2: Remembering/Understanding
Chapter Section: 13.2
22) Horizontal gene transfer is one plausible explanation as to why organisms in Archaea, Bacteria, and
Eukarya still share so many genes among such distinct domains.
Answer: TRUE
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.3
13.3 Essay Questions
1) Explain the endosymbiotic theory. What is the evolutionary value of endosymbiosis?
Answer: The theory states that a chemoorganotrophic bacterium and a cyanobacterium were stably incorporated into a cell and gave rise to a mitochondrion and chloroplast (respectively), which formed a eukaryotic cell. Endosymbiosis provides a mutualistic relationship where the incorporated cells are protected from direct contact with the environment, and the cell that incorporated the cells gains metabolic diversity.
Blooms Taxonomy: 3-4: Applying/Analyzing
Chapter Section: 13.4
2) Describe the hydrogen hypothesis and why it is favored over other hypotheses.
Answer: The hydrogen hypothesis states that a hydrogen-consuming archaea served as a host for the stable incorporation of a hydrogen-producing facultative anaerobic bacterium. This hypothesis describes the first eukaryotic cells as ones without nuclei. It accounts for eukaryotes having bacteria-like ATP-producing pathways in hydrogenosomes and the presence of bacteria-like lipids in eukaryotes. Neither of these is accounted for in other hypotheses that state that eukaryotes first contained nuclei and lacked mitochondria.
Blooms Taxonomy: 5-6: Evaluating/Creating
Chapter Section: 13.4
3) Carl Woese was an important figure in microbial classification and changed our understanding of the evolution and diversity of life. What breakthrough did he make that allowed us to infer evolutionary relationships between organisms? What assumptions was his breakthrough based on?
Answer: During the 1970s, Dr. Carl Woese pioneered the usage of SSU rRNA genes for phylogenetic analysis. He realized that SSU rRNA genes could be used to infer evolutionary relationships because they were (1) universally distributed, (2) have the same function in every organism, (3) change slowly over evolutionary time (highly conserved), and (4) of adequate length to provide sufficient information about very deep, or old, evolutionary relationships. He assumed that changes in DNA sequence are reliably passed on to offspring (they are heritable) and that nucleotide changes between two organisms will accumulate over time since they last shared a common ancestor. Homologous sequence comparison thus allows us to infer evolutionary relationships betwee
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