Test Bank for Brock Biology of Microorganism 15tH Ed By by Michael T. Madigan

Test Bank for Brock Biology of Microorganism 15tH Ed By by Michael T. Madigan

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WITH ANSWERS

 

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

1. A) the ABC transport system.
2. B) group translocation.
3. C) symport.
4. D) simple transport.

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

1. A) metabolism.
2. B) anabolism.
3. C) catabolism.
4. D) synthatabolism.

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?

1. A) organic compounds
2. B) inorganic compounds
3. C) both organic and inorganic compounds
4. D) neither organic nor inorganic compounds

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?

1. A) C2H3O2-
2. B) H2
3. C) CO2
4. D) H+

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.3

 

 

5) Which of the following statements is FALSE?

1. A) Most bacteria are capable of using ammonia as their sole nitrogen source.
2. B) Some bacteria are able to use nitrates or nitrogen gas as their nitrogen source.
3. C) Most available nitrogen is in organic forms.
4. D) Nitrogen is a major component of proteins and nucleic acids.

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.6

6) All microorganisms require

1. A) carbon, iron, and sodium.
2. B) phosphorus, aluminum, and sodium.
3. C) calcium, potassium, and magnesium.
4. D) phosphorus, selenium, and sulfur.

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?

1. A) iron
2. B) hydrogen
3. C) zinc
4. D) magnesium

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.

1. A) before enzyme production
2. B) during enzyme production
3. C) after enzyme production
4. D) at any pointbefore, during, or after enzyme production

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

1. A) the amount of energy catalysts required for biosynthesis or catabolism.
2. B) the potential metabolic reaction rate.
3. C) whether there will be a requirement or production of energy.
4. D) energy stored in each compound.

Answer:  C

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  3.4

 

10) Which is an example of a micronutrient?

1. A) arginine
2. B) inorganic phosphorous
3. C) iron
4. D) vitamin B12

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.1

11) Aseptic technique refers to

1. A) the microbial inoculum placed into a test tube or onto a Petri plate.
2. B) a series of practices to avoid contamination.
3. C) the autoclave and other sterilizing procedures.
4. D) cleanliness in the laboratory.

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.

1. A) complex / minimal
2. B) minimal / complex
3. C) selective / complex
4. D) selective / differential

Answer:  A

Blooms Taxonomy:  5-6: Evaluating/Creating

Chapter Section:  3.2

 

13) If G0 is negative, the reaction is

1. A) exergonic and requires the input of energy.
2. B) endergonic and requires the input of energy.
3. C) exergonic and energy will be released.
4. D) endergonic and energy will be released.

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.4

 

14) Activation energy is the energy

1. A) required for a chemical reaction to begin.
2. B) given off as the products in a chemical reaction are formed.
3. C) absorbed as G0 moves from negative to positive.
4. D) needed by an enzyme to catalyze a reaction without coenzymes.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.5

 

 

15) A catalyst

1. A) requires more reactants but makes the reaction rate faster.
2. B) increases the amount of reactants produced but does not change the rate.
3. C) changes the rate of the reaction but does not change the end amount of products.
4. D) changes both the rate of a reaction and the amount of the product that will be obtained as

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

1. A) substrate complex.
2. B) active site.
3. C) catalytic site.
4. D) junction of van der Waals forces.

Answer:  B

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.5

 

17) What is the difference between a coenzyme and a prosthetic group?

1. A) Coenzymes are essential for an enzymes function and prosthetic groups only enhance its reaction rate.
2. B) Coenzymes are weakly bound whereas prosthetic groups are strongly bound to their respective enzymes.
3. C) Coenzymes are organic cofactors and prosthetic groups are inorganic cofactors.
4. D) Coenzymes require additional ions to bind to enzymes but prosthetic groups are able to directly interact with enzymes.

Answer:  B

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  3.5

 

18) If an oxidation reaction occurs

1. A) simultaneous reduction of a different compound will also occur, because electrons do not generally exist alone in solution.
2. B) another oxidation reaction will occur for a complete reaction, because one oxidation event is considered a half reaction.
3. C) a cell is undergoing aerobic respiration, because oxygen is being used.
4. D) a reduction reaction would not occur, because they are opposite reaction mechanisms.

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

1. A) carbohydrates.
2. B) DNA.
3. C) lipids.
4. D) proteins.

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

1. A) oxygen.
2. B) carbon.
3. C) nitrogen.
4. D) phosphorous.

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

1. A) oxygen.
2. B) carbon.
3. C) nitrogen.
4. D) carbon and oxygen.

Answer:  D

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  3.3

 

22) The Embden-Meyerhof-Parnas pathway is another name for

1. A) the citric acid cycle.
2. B) glycolysis.
3. C) electron transport.
4. D) NADH production.

Answer:  B

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.8

 

23) The net gain of ATP per molecule of glucose fermented is

1. A) 1.
2. B) 2.
3. C) 4.
4. D) 8.

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?

1. A) acetyl~S-CoA
2. B) glycogen
3. C) adenosine triphosphate
4. D) H2

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

1. A) more reducing equivalents are used for anaerobic catabolism.
2. B) less ATP is consumed during the first stage of aerobic catabolism.
3. C) oxidative phosphorylation yields a lot of ATP.
4. D) substrate-level phosphorylation yields a lot of ATP.

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

1. A) ATP and regenerated NAD+; the fermentation products are waste products.
2. B) ethanol or lactate; ATP is a waste product.
3. C) CO2; ATP is a waste product.
4. D) not relevant because glycolysis is not a major pathway.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.8

 

27) In aerobic respiration, the final electron acceptor is

1. A) hydrogen.
2. B) oxygen.
3. C) water.
4. D) ATP.

Answer:  B

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.10

 

28) Which of the following is NOT membrane-associated?

1. A) NADH dehydrogenases
2. B) flavoproteins
3. C) cytochromes
4. D) Cytochromes, flavoproteins, and NADH dehydrogenases all can be membrane-associated.

Answer:  D

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.10

 

 

29) During electron transport reactions

1. A) OH- accumulates on the outside of the membrane while H+ accumulates on the inside.
2. B) OH- accumulates on the inside of the membrane while H+ accumulates on the outside.
3. C) both OH- and H+ accumulate on the inside of the membrane.
4. D) both OH- and H+ accumulate on the outside of the membrane.

Answer:  B

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.11

 

30) The rising of bread dough is the result of

1. A) biotin production.
2. B) carbon dioxide produced by fermentation.
3. C) oxidative phosphorylation.
4. D) oxygen being released.

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?

1. A) only -ketoglutarate
2. B) only oxaloacetate
3. C) only succinyl-CoA
4. D) -ketoglutarate, oxaloacetate, and succinyl-CoA

Answer:  D

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.9

 

32) Microbial growth on the two-carbon acetate substrate invokes

1. A) the citric acid cycle for aerobic catabolism.
2. B) both the citric acid and glyoxylate pathways.
3. C) the glyoxylate pathway.
4. D) the glyoxylate and glycolysis pathways.

Answer:  B

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.9

 

33) Which is one major difference between anaerobic and aerobic respiration?

1. A) electron donor
2. B) electron acceptor
3. C) use of electron transport
4. D) use of proton motive force

Answer:  B

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  3.12

 

 

34) For a carbon source, chemoorganotrophs generally use compounds such as

1. A) acetate, succinate, and glucose.
2. B) bicarbonate and carbon dioxide.
3. C) nitrate and nitrite.
4. D) acetate, bicarbonate, and nitrate.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.3

 

35) All of the following are non-protein electron carriers EXCEPT

2. A) FADH2.
3. B) FMNH2.
4. C) cytochromes.
5. D) quinones.

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.10

36) Which two metabolic processes are most dissimilar?

1. A) citric acid cycle and glycolysis
2. B) glycolysis and gluconeogenesis
3. C) proton motive force and substrate-level phosphorylation
4. D) pentose phosphate pathway and glycolysis

Answer:  B

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.13

 

37) How does the proton motive force lead to production of ATP?

1. A) ATPase requires one proton to make one ATP.
2. B) Protons must be pumped against a concentration gradient from outside of the cell into the cell to rotate the F0 subunit of ATPase for the F1 subunit to make ATP.
3. C) Oxidative phosphorylation of ADP by ATP synthase requires protons as cofactors in the reaction.
4. D) Translocation of three to four protons drives the F0 component of ATPase which in turn phosphorylates one ADP into ATP.

Answer:  D

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.11

 

38) Five-carbon sugars are used in the

1. A) biosynthesis of DNA and RNA.
2. B) catabolic pentose phosphate pathway for carbon and energy.
3. C) biosynthesis of DNA and RNA as well as catabolic pentose phosphate pathway.
4. D) activation of pentoses to form glycogen for energy storage.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  3.13

 

39) Improperly functioning acyl carrier proteins (ACPs) would likely result in

1. A) a physiological shift to anaerobic metabolism where an energized membrane is less important for energy production.
2. B) enhanced growth of a bacterium due to faster growth substrate uptake by a weakened membrane.
3. C) no harm to bacteria, because only archaeons and eukaryotes use ACPs for fatty acid biosynthesis.
4. D) death for a bacterium due to poor lipid bilayer integrity.

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.

1. A) degrade an amino acid or nucleic acid
2. B) invoke the pentose phosphate pathway
3. C) degrade a fatty acid
4. D) use a broad specificity phosphatase with inorganic phosphatase and NADH

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

1. A) NADH.
2. B) water.
3. C) nitrate.
4. D) FMN.

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?

1. A) Cells require much less P to grow than N, so extra P will be used for ATP synthesis and result in a faster growth rate.
2. B) Cells will never consume all of the phosphate, because N is needed in higher quantities than P.
3. C) The final biomass of cells will be no different than if only 50% of the phosphate was provided.
4. D) The bacteria will import all of the ammonia to use for biosynthetic pathways.

Answer:  A

Blooms Taxonomy:  5-6: Evaluating/Creating

Chapter Section:  3.3

 

 

43) Most of the carbon in amino acid biosynthesis comes from

1. A) citric acid cycle intermediates.
2. B) citric acid cycle intermediates and glycolysis products.
3. C) glycolysis products.
4. D) glycolysis intermediates and products.

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?

1. A) citric acid cycle
2. B) glycolysis
3. C) gluconeogenesis
4. D) pentose phosphate pathway

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

1. A) a higher diversity of cytochromes would likely be observed.
2. B) cytochromes would be unnecessary for cells and quinones would be more important.
3. C) Q-cycle reactions would no longer be necessary for electron transport, but the proton motive force would otherwise be unchanged.
4. D) most metabolic pathways for both anabolism and catabolism would have to be rewritten.

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?

1. A) aerobic catabolism
2. B) fermentation
3. C) chemoorganotrophy
4. D) photoautrophy

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

1. A) anoxygenic phototrophs.
2. B) anoxygenic lithotrophs.
3. C) oxygenic phototrophs.
4. D) oxygenic lithotrophs.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.2

 

2) What two gases were most abundant on early Earth?

1. A) O2 and CO2
2. B) N2 and H2
3. C) CO2 and H2
4. D) CO2 and N2

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

1. A) considerably warmer.
2. B) considerably colder.
3. C) about the same as today.
4. D) about the same as today on average, but the diurnal fluctuations were much greater.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.1

 

4) The earliest RNA probably functioned in

1. A) catalysis.
2. B) self-replication.
3. C) both catalysis and self-replication.
4. D) neither catalysis nor self-replication.

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.

1. A) Fe, O2, and H2
2. B) S, O2, and H2
3. C) S, and O2
4. D) S, and H2

Answer:  D

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.1

6) Evolution is driven by

1. A) random mutation.
2. B) novel metabolic pathways.
3. C) selection pressure.
4. D) selection pressure applied to random mutation.

Answer:  D

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  13.5

 

7) Microorganisms were probably restricted to the oceans and subsurface environments until

1. A) aquatic life brought them onto land.
2. B) chemoorganotrophy developed.
3. C) phototrophy evolved.
4. D) the ozone layer was made.

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?

1. A) Nucleotide changes accumulate in a sequence in proportion to time.
2. B) Nucleotide changes are generally NOT transferred to progeny.
3. C) Nucleotide changes are NOT random.
4. D) Nucleotide changes are subject to intense selective pressure.

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.

1. A) ATPase
2. B) electron transport
3. C) SSU rRNA
4. D) tRNA

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.7

 

10) A monophyletic group is a group that

1. A) descended from one ancestor.
2. B) has the same fitness level.
3. C) possesses one taxonomic trait that is the same.
4. D) shares one phylogenetic marker.

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)

1. A) alleles.
2. B) MLST.
3. C) horizontal gene transfers.
4. D) ribotypes.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.5

 

12) A key concept in evolution is that all mutations are

1. A) random.
2. B) neutral.
3. C) deleterious.
4. D) either deleterious or beneficial.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.5

 

13) LUCA is

1. A) the last universal common ancestor.
2. B) the individual ancestor of each of the three domains.
3. C) actually somewhat of a misnomer because it is now believed that each of the domains arose independently.
4. D) All of the answers are correct.

Answer:  A

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.3

 

 

14) Horizontal gene transfer

1. A) is so rare over evolutionary history that it is not considered when examining microbial evolution.
2. B) occurs within bacterial species.
3. C) complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution.
4. D) only affects the evolution of plasmids.

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

1. A) Crenarchaeota.
2. B) cyanobacteria.
3. C) iron-oxidizing bacteria.
4. D) Alphaproteobacteria.

Answer:  D

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.4

16) Which statement most closely expresses our present understanding?

1. A) The chloroplast is an ancestor of the cyanobacteria.
2. B) The cyanobacteria are descendents of the chloroplast.
3. C) The chloroplast arose from the incorporation of a cyanobacterial-like organism.
4. D) The chloroplast and the cyanobacteria are not closely (or specifically) related.

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?

1. A) Two months is not long enough for different fitness levels to evolve even if the genotype frequencies change.
2. B) This result is not possible because different genotype frequencies would result in different fitness levels under the same growth conditions.
3. C) Natural selection caused the evolution of different genotype frequencies within the separate test tubes.
4. D) Genetic drift within the small populations in the test tubes resulted in different genotype frequencies.

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

1. A) evolve identical adaptations to use the nitrogen source provided in the media.
2. B) not change or adapt very much over this small number of generations.
3. C) each accumulate different random mutations resulting in different adaptations to use the nitrogen in the media.
4. D) direct mutations to occur in nitrogen utilization and uptake genes in order to adapt rapidly to the culture conditions.

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

1. A) may increase fitness of a microorganism by eliminating unneeded genes.
2. B) always result in a severe loss of fitness for the microorganism.
3. C) are uncommon because they are usually lethal.
4. D) always result in a severe loss of fitness but keep microbial genomes compact.

Answer:  A

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  13.6

20) Polyphasic taxonomy uses methods that include

1. A) phenotypic methods.
2. B) genotypic methods.
3. C) phylogenetic methods.
4. D) phenotypic, genotypic, and phylogenetic methods.

Answer:  D

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.6

 

21) Ribotyping

1. A) bypasses sequencing and sequence alignments.
2. B) exploits unique DNA restriction patterns.
3. C) allows discrimination between species and different strains of a species.
4. D) bypasses sequencing and sequence alignments, exploits unique DNA restriction patterns, and allows discrimination between species and different strains of a species.

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?

1. A) hyperthermophilic
2. B) aerobic metabolism
3. C) small genome
4. D) branching near the root of the evolutionary tree of life

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

1. A) domains.
2. B) families.
3. C) orders.
4. D) strains or species.

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?

1. A) fluorescence in situ hybridization
2. B) DNA-DNA hybridization
3. C) multilocus sequence typing
4. D) fatty acid methyl ester analysis

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

1. A) Bacteria.
2. B) Archaea.
3. C) Eukarya.
4. D) LUCA.

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

1. A) sulfide oxidation.
2. B) nitrification.
3. C) iron oxidation.
4. D) sulfide oxidation, nitrification, and iron oxidation.

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

1. A) classified as individual strains of the same species.
2. B) classified as individual species of the same genus.
3. C) split into different families.
4. D) classified as the same species if they can mate via conjugation.

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

1. A) bottleneck events.
2. B) horizontal gene transfer.
3. C) substitutions.
4. D) substitution and bottleneck events.

Answer:  B

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  13.6

 

29) Microbial ________ studies the diversity of microorganisms and links their phylogeny with ________.

1. A) taxonomy / genotype
2. B) phylogeny / phenotype
3. C) taxonomy / phenotype
4. D) systematics / taxonomy

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?

1. A) nitrate
2. B) elemental sulfur
3. C) ferrous iron
4. D) hydrogen sulfide

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?

 

1. A) Species E is more closely related to species A than to species D.
2. B) Species D is more closely related to species C than to species E.
3. C) Species F is more closely related to species D than to species E.
4. D) Species C is more closely related to species B than to species D.

Answer:  B

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  13.7

 

32) The early energy reactions used hydrogen, which is a powerful

1. A) oxidant.
2. B) electron donor.
3. C) electron acceptor.
4. D) stabilizer.

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.

1. A) hydrogen
2. B) elemental sulfur
3. C) ferrous iron
4. D) nitrate

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 ________.

1. A) ozone / UV radiation
2. B) elemental sulfur / volcanism
3. C) ferrous iron / hydroxylating radicals
4. D) sulfate / hydrogen sulfide

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 ________.

1. A) nucleus / Golgi body
2. B) mitochondrion / chloroplast
3. C) endoplasmic reticulum / Golgi body
4. D) hydrogenosome / chloroplast

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?

1. A) The core genome consists of all the nucleic acid polymerases and translation enzymes, while the pan genome consists of all the biosynthetic pathways.
2. B) The core genome is the set of genes within the mitochondria, while the pan genome is the set of genes in the nucleus of a species.
3. C) The core genome is a set of genes shared by all members of a species, while the pan genome includes the core genes as well as genes that are not shared by all members.
4. D) The core genome is the set of genes introduced by horizontal gene transfer, while the pan genome is the set of genes that is not transferred horizontally.

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?

1. A) highly conserved
2. B) universally distributed
3. C) transferred horizontally between species
4. D) highly conserved and universally distributed

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?

1. A) Previous versions of the universal tree of life were based largely on fossils and comparative biology, which overlooked the diversity of and relationships between most prokaryotes.
2. B) The current universal tree of life is supported by multiple genes including SSU rRNA sequences.
3. C) The current universal tree of life depicts three domains of life, two of which are prokaryotic.
4. D) The current universal tree of life is based on molecular sequences and completely changes our view of evolutionary relationships between eukaryotic species.

Answer:  D

Blooms Taxonomy:  3-4: Applying/Analyzing

Chapter Section:  13.3

 

39) ________ formed the semipermeable membrane-like surfaces for the earliest life forms.

1. A) Proteins
2. B) Hydrogen sulfide
3. C) Lipid bilayers
4. D) RNA

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.4

 

40) The first catalytic and self-replication biological molecule was most likely

1. A) RNA.
2. B) DNA.
3. C) proteins.
4. D) ATP.

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 ________.

1. A) taxonomy / phenotype
2. B) phylogeny / nucleotide sequence data
3. C) phylogeny / phenotype
4. D) taxonomy / morphology

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.

1. A) topology
2. B) neighbor joining
3. C) parsimony
4. D) systematics

Answer:  C

Blooms Taxonomy:  1-2: Remembering/Understanding

Chapter Section:  13.7

 

43) Multilocus sequence typing (MLST) involves sequencing several different

1. A) genomes.
2. B) housekeeping genes.
3. C) tRNA genes.
4. D) rRNA genes.

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.

1. A) whole genome analysis
2. B) microscopy
3. C) staining
4. D) pigments

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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