Test Bank Brock Biology of Microorganisms 14th Edition By Michael T. Madigan

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Test Bank Brock Biology of Microorganisms 14th Edition By Michael T. Madigan

 

 

Brock Biology of Microorganisms, 14e (Madigan et al.)

Chapter 3  Microbial Metabolism

 

Multiple Choice Questions

 

1) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.13

 

2) Based on the functional roles of phosphate in various microbial metabolisms, deduce which compounds phosphate exists as in microorganisms.

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

Answer:  C

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.1

 

3) 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.3

 

4) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.1

 

 

5) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.1

6) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.1

 

7) Based on your understanding of metabolism, generalize when an enzyme’s 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 point–before, during, or after enzyme production

Answer:  C

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.5

 

8) 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

Bloom’s Taxonomy:  Application

Chapter Section:  3.4

 

9) Which is an example of a micronutrient?

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

Answer:  C

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.1

 

10) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.2

11) 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

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.2

 

12) If ΔG0′ 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.4

 

13) Activation energy is the energy

  1. A) required to transform all reactants into their reactive state.
  2. B) given off as the products in a chemical reaction are formed.
  3. C) absorbed as ΔG0′ moves from negative to positive.
  4. D) needed by an enzyme to catalyze a reaction without coenzymes.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.5

 

14) 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.5

 

15) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.5

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

  1. A) Coenzymes are essential for an enzyme’s 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

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.5

 

17) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.6

 

18) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.1

 

 

19) 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

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.3

 

20) 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

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.3

21) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.8

 

22) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.8

 

23) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.8

 

24) 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.8

 

25) From the standpoint of the microorganism, in glycolysis the crucial product is

  1. A) ATP; 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.8

26) In aerobic respiration, the final electron acceptor is

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

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.10

 

27) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.10

 

28) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.11

 

 

29) 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

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.11

 

30) Which intermediate compound(s) in the citric acid cycle is/are often used for biosynthetic pathways as well as carbon catabolism?

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

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.12

31) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.12

 

32) Which feature of anaerobic and aerobic respiration is different between the two catabolic strategies?

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

Answer:  B

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.13

 

33) 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.3

 

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

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

Answer:  C

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.10

 

35) 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.14

36) 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 F0subunit of ATPase for the F1subunit 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 F0component of ATPase which in turn phosphorylates one ADP into ATP.

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.11

 

37) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.14

 

 

38) 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

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.16

 

39) 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

Bloom’s Taxonomy:  Application

Chapter Section:  3.14

 

40) 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

Bloom’s Taxonomy:  Application

Chapter Section:  3.14

41) 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

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.1

 

 

42) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.15

 

43) 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

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.15

 

44) Hypothetically, if electron pools 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

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.11

 

45) Which metabolic strategy does NOT invoke the proton motive force for energy conservation?

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

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.13

 

True/False Questions

 

1) 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

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.1

 

2) Regeneration of oxaloacetate is essential for the citric acid cycle to be cyclical.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.12

 

3) Depending on the particular metabolism of a bacterium, electron transport can be used to energize and rotate ATP synthase.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.11

 

4) Each amino acid made during protein biosynthesis first requires a separate biosynthetic pathway to be invoked by a cell.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.15

 

5) The terminating step of moving electrons onto oxygen releases additional ATP during aerobic metabolism not made during anaerobic growth.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.11

 

6) Nitrogenases not only reduce N2 but also can act on acetylene (C2H2).

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.17

 

7) 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

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.7

 

 

8) 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

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.5

9) Free-energy calculations are dependent on the rates of the reactions.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.4

 

10) With respect to nitrogen utilization, relatively few bacteria can use NH3 whereas many more can make use of N2.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.17

 

11) The proton motive force is most often generated by splitting of H2.

Answer:  FALSE

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.11

 

12) Biosynthesis of glucose can occur by compounds other than sugars via gluconeogenesis.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.14

 

13) If a substance is reduced, it gains electrons.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.6

 

14) Molebdenum is a cofactor for nitrogenase, which means every nitrogen-fixing microorganisms will not be able to fix nitrogen without Mo.

Answer:  TRUE

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.17

 

15) Magnesium is not considered a growth factor for microorganisms, because growth factors are always organic compounds.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.1

 

 

16) 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

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.10

 

17) Varied coenzyme availability increases the diversity of enzymatic reactions in both biosynthetic and catabolic pathways possible in a cell.

Answer:  TRUE

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.5

18) The energy released from the hydrolysis of coenzyme A is conserved in the synthesis of ATP.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.7

 

19) In substrate-level phosphorylation, ATP storage is depleted during the steps in catabolism of the fermentable compounds.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.8

 

20) Catabolic pathways are essential for microorganisms to obtain energy, because biosynthetic reactions for cellular growth generally require energy input.

Answer:  TRUE

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.12

 

21) In electron transport systems, the electron carriers are membrane associated.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.11

 

22) Heme prosthetic groups are involved in electron transfer with quinones.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.5

 

23) During the electron transport process, protons and electrons become physically separated in the cell membrane.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.10

 

 

24) 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

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.16

 

25) The net result of electron transport is the generation of a pH gradient and an electrochemical potential across the membrane.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.11

 

26) 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

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.15

Essay Questions

 

1) 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.

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.2

 

2) 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.

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.6

 

 

3) 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.

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.12

 

4) 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.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.11

 

5) 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.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.12

6) 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.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.12

 

7) 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.

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.17

 

8) Differentiate between exergonic and endergonic in terms of free-energy calculations.

Answer:  A positive change in free energy (ΔG0′) means the reaction needs energy input to occur (called endergonic), whereas a negative ΔG0′ needs no energy input and actually releases excess energy (called exergonic).

Bloom’s Taxonomy:  Analysis

Chapter Section:  3.4

 

9) 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.

Bloom’s Taxonomy:  Knowledge

Chapter Section:  3.5

 

10) 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 brewer’s 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.

Bloom’s Taxonomy:  Evaluation

Chapter Section:  3.9

11) 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 ΔE0′.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  3.6

 

 

12) Consider a pizza dough made by vigorously mixing to form gluten and evenly disperse the ingredients such as baker’s 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.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  3.6

Brock Biology of Microorganisms, 14e (Madigan et al.)

Chapter 13  Metabolic Diversity of Microorganisms

 

Multiple Choice Questions

 

1) The metabolic diversity of photosynthetic bacteria stems from different

  1. A) bacteriochlorophylls and pigments they contain.
  2. B) chlorophylls they can have and organic compounds they can produce.
  3. C) light-harvesting complexes, electron donors, and organic compounds they produce.
  4. D) unrelated taxa capable of photosynthesis.

Answer:  C

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

 

2) Whether an organism is classified as a photoheterotroph or a photoautotroph depends on its

  1. A) energy source.
  2. B) carbon source.
  3. C) oxygen requirements.
  4. D) carbon and energy sources.

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

 

3) In photosynthesis, NADH and NADPH are produced from NAD+ and NADP+ by

  1. A) oxidation reactions.
  2. B) reduction reactions.
  3. C) both oxidation and reduction reactions.
  4. D) neither oxidation nor reduction reactions.

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

 

4) Bacteriochlorophyll and chlorophyll contain ________ as a cofactor.

  1. A) iron (II)
  2. B) iron (III)
  3. C) magnesium
  4. D) manganese

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.1

 

 

5) In contrast to chlorophylls, carotenoids function

  1. A) as accessory pigments that enable absorption of energy from higher wavelengths.
  2. B) primarily as photoprotection (but they also transfer some absorbed energy into reaction centers).
  3. C) to convert reactive oxygen species into usable energy.
  4. D) to quench toxic oxygen species.

Answer:  D

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.2

6) Proteomic analysis of a microbial community indicated an abundance of phycobiliproteins. Which phototrophic group is likely active and abundant in this community?

  1. A) cyanobacteria
  2. B) eukaryotic phototrophs
  3. C) green bacteria
  4. D) prochlorophytes

Answer:  A

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.2

 

7) At some of the lowest light concentrations, ________ can still grow well due to their ________, which effectively harvest photons for energy.

  1. A) green bacteria / antenna pigments
  2. B) green bacteria / chlorosomes
  3. C) purple bacteria / antenna pigments
  4. D) purple bacteria / chlorosomes

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.2

 

8) Light energy passes from phycobiliproteins to reaction centers in

  1. A) cyanobacteria.
  2. B) green sulfur bacteria.
  3. C) purple bacteria.
  4. D) most photosynthetic bacteria.

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.2

 

9) Two separate photosystems involved in electron flow is a hallmark of

  1. A) anoxygenic phototrophs.
  2. B) green sulfur bacteria.
  3. C) oxygenic phototrophs.
  4. D) purple bacteria.

Answer:  C

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.4

 

10) Intracytoplasmic membrane systems housing vesicles known as chromatophores, which function in photosynthesis, are commonly found in

  1. A) algae.
  2. B) green sulfur bacteria.
  3. C) most autotrophic organisms.
  4. D) purple phototrophic bacteria.

Answer:  D

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

11) “Special pair” is the name given to the ________ in the photochemical complex of the purple bacteria.

  1. A) two bacteriochlorophyll a molecules
  2. B) two bacteriochlorophyll b molecules
  3. C) two quinones
  4. D) two reaction centers

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.3

 

12) What will happen to a cyanobacterium that has its photosystem II (PSII) blocked?

  1. A) Additional electron acceptors, such as NADP+, will be required to oxidize oxygen and overcome the lost PSII process.
  2. B) Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H2
  3. C) It will die from being unable to obtain energy for photosynthesis.
  4. D) Photons will generate excessive reactive oxygen species and the cyanobacterium will die as a consequence.

Answer:  B

Bloom’s Taxonomy:  Evaluation

Chapter Section:  13.4

 

13) Which group of microorganisms would the Calvin cycle LEAST likely be found in?

  1. A) anoxygenic Bacteria
  2. B) chemolithotrophic Bacteria
  3. C) cyanobacteria
  4. D) hydrocarbon catabolizing Bacteria

Answer:  D

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.5

 

 

14) The process by which electrons from the quinone pool are forced against the thermodynamic gradient to reduce NAD+ to NADH is called reverse

  1. A) proton motive force.
  2. B) reduction.
  3. C) electron transport.
  4. D) energy flow.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.3

 

15) The path of electron flow in oxygenic phototrophs is referred to as the ________ scheme.

  1. A) E
  2. B) S
  3. C) Q
  4. D) Z

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.4

16) Plastocyanin is a

  1. A) membrane-bound sac found in certain bacteria.
  2. B) photosynthetic pigment found in some bacteria.
  3. C) copper-containing protein in photosystem II that donates electrons to photosystem I.
  4. D) blue-green bacterium known for its unusual photoreactive complex.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.4

 

17) The Calvin cycle

  1. A) is responsible for the fixation of CO2into cell material.
  2. B) utilizes both NAD(P)H and ATP.
  3. C) requires both ribulose bisphosphate carboxylase and phosphoribulokinase.
  4. D) uses CO2, NAD(P)H, and ATP to make biomass with ribulose bisphosphate carboxylase and phosphoribulokinase.

Answer:  D

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.5

 

 

18) Regarding CO2 fixation mechanisms in the autotrophic green sulfur bacteria,

  1. A) Chlorobium uses the reverse citric acid cycle, and Chloroflexus uses the hydroxypropionate pathway.
  2. B) Chlorobium uses the hydroxypropionate pathway, and Chloroflexus uses the reverse citric acid cycle.
  3. C) both Chlorobium and Chloroflexus use the reverse citric acid cycle.
  4. D) both Chlorobium and Chloroflexus use the hydroxypropionate pathway.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.5

 

19) In most cases, the final product of sulfur oxidation is

  1. A) hydrogen sulfide.
  2. B) elemental sulfur.
  3. C) sulfate.
  4. D) thiosulfate.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.8

 

20) Identifying carboxysomes in a bacterium suggests it

  1. A) contains the reverse citric acid cycle.
  2. B) has a deficient Calvin cycle and accumulated CO2.
  3. C) is in a carboxylic acid rich environment and is storing excess quantities for potentially harsh conditions.
  4. D) will use the Calvin cycle convert the concentrated CO2into biomass.

Answer:  D

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.5

21) Ferrous iron (Fe2+) oxidation generally occurs in environments with

  1. A) alkaline conditions.
  2. B) high H+
  3. C) high oxygen content.
  4. D) little or no light present.

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.9

 

 

22) Alternative autotrophic routes to the Calvin cycle such as the reverse citric acid cycle and the hydroxypropionate pathway are unified in their requirement for

  1. A) CO2.
  2. B) coenzyme A.
  3. C) NAD(P)H.
  4. D) organic compound(s) formed.

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.5

 

23) The aerated upper layer of soil is likely to have ________ concentrations of H2 for aerobic H2-oxidizing Bacteria, so these bacteria likely ________.

  1. A) high / thrive in such conditions by not competing with chemoorganotrophs
  2. B) high / generate important reducing equivalents as byproducts for other microorganisms in the soil
  3. C) low / do not occur in such habitats
  4. D) low / will need a chemoorganotrophic way to grow as well

Answer:  D

Bloom’s Taxonomy:  Evaluation

Chapter Section:  13.7

 

24) What metabolic advantage do cells have in storing the elemental sulfur byproduct from sulfide oxidation?

  1. A) The cells avoid producing transport energy waste to secrete the sulfur.
  2. B) The byproduct serves as an electron reserve for subsequent oxidation.
  3. C) Sulfur decreases the intracellular acidification for non-acid-tolerant sulfide oxidizers.
  4. D) The byproduct can be used for other biosynthetic pathways that use sulfur, such as Rieske Fe-S proteins.

Answer:  B

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.8

 

25) A cell that lacks sulfite oxidase but can still oxidize sulfur for energy could be identified by

  1. A) adenosine phosphosulfate reductase coupled with substrate-level phosphorylation.
  2. B) electrons being transferred to cytochrome c prior to shuttling them into the electron transport chain.
  3. C) identifying an alternative quinone, flavoprotein, or cytochrome.
  4. D) quantifying the release of sulfate byproduct.

Answer:  A

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.8

 

26) The only organisms that perform photosynthesis are ones that produce some form of

  1. A) chlorophyll or bacteriochlorophyll.
  2. B) carotenoids.
  3. C) phycoerythrin.
  4. D) phycocyanin.

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.2

 

27) Which of the following are NOT found within the photosynthetic gene cluster of Rhodobacter (a purple phototrophic bacterium)?

  1. A) genes encoding reaction center and light-harvesting photocomplexes
  2. B) genes encoding proteins involved in phycobiliprotein biosynthesis
  3. C) genes encoding proteins involved in bacteriochlorophyll biosynthesis
  4. D) genes encoding proteins involved in carotenoid biosynthesis

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.2

 

28) Anammox is an anaerobic process that generates energy from ________ and forms N2.

  1. A) ammonia
  2. B) ammonium
  3. C) ammonia and nitrate
  4. D) ammonia and nitrite

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.10

 

29) What would likely occur if an anammox bacterium was unable to use ladderane lipids?

  1. A) Ammonium rather than ammonia would be used due to ammonia toxicity to other cellular processes.
  2. B) It would require a different source for carbon assimilation.
  3. C) Rates of anammox would be considerably slower due to a lack of localized metabolism.
  4. D) Reactive nitrogen species would kill the cell.

Answer:  D

Bloom’s Taxonomy:  Evaluation

Chapter Section:  13.10

 

30) Which of the following reactions is classified as a heterofermentation?

  1. A) hexose 2 lactate + 2 H+
  2. B) HCOOH H2+ CO2
  3. C) glucose lactate + ethanol + CO2+ H+
  4. D) fructose 3 acetate + 3 H+

Answer:  C

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.12

31) Glucose fermentation by Clostridium spp. produce ATP only when acetate and butyrate are produced. Why do these organisms produce acetone and butanol after strong initial activity of generating ATP with acetate and butyrate byproducts?

  1. A) Acetate and butyrate accumulation creates a deadly acidic environment, which acetone and butanol do not.
  2. B) Acetate and butyrate are no longer needed for biosynthetic pathways.
  3. C) Acetone and butanol serve as better sources for NAD(P)+
  4. D) Acetone and butanol production is favored for stability to store intracellular carbon sources for potential nutrient poor conditions.

Answer:  A

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.13

 

32) The foul-smelling putrescine byproduct suggests activity of

  1. A) amino acid fermentation by clostridia.
  2. B) secondary fermentation.
  3. C) sulfur-oxidizing bacteria.
  4. D) syntrophic carbohydrate metabolism.

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.13

 

33) A bacterium that catabolizes a compound by linking ion pumps to establish a proton or sodium motive force for energy

  1. A) can circumvent substrate-level and oxidative phosphorylation.
  2. B) makes insufficient energy to grow but enough for cellular maintenance to survive.
  3. C) requires a second bacterium to cooperatively drive the gradient.
  4. D) still requires another carbon substrate to provide a carbon source.

Answer:  A

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.14

 

34) Which metabolic strategy’s existence suggests rapid growth is NOT always the best strategy to survive in the environment?

  1. A) anaerobic fermentation
  2. B) disproportionation
  3. C) methylotrophy
  4. D) syntrophy

Answer:  D

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.15

 

 

35) Obligate anaerobes can often use ________ electropositive redox couples than facultative anaerobes, and ________ metabolism is most common in this group as well.

  1. A) lower / assimilative
  2. B) lower / dissimilative
  3. C) higher / assimilative
  4. D) higher / dissimilative

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.16

36) In Bacteria, the MOST common oxidized form of nitrogen is ________ and of sulfur is ________.

  1. A) nitrate / sulfate
  2. B) nitrate / sulfite
  3. C) nitrite / sulfate
  4. D) nitrite / sulfite

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.18

 

37) Anaerobic fermentation often provides CO2, which can be used by ________ as an electron acceptor for energy.

  1. A) acetogens
  2. B) methanotrophs
  3. C) methanogens
  4. D) acetogens and methanogens

Answer:  D

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.19

 

38) How is ATP made by an acetogen during CO2 fixation?

  1. A) Electrons from metal cofactors energize the electron transport chain and drive the proton motive force to activate ATP synthase.
  2. B) Substrate-level phosphorylation of ADP occurs when coenzyme A is removed from acetyl-CoA.
  3. C) It is made by substrate-level phosphorylation and a Na+-translocating ATPase.
  4. D) The energized CO-CH3 complex during thioesterification drives a Na+-translocating ATPase.

Answer:  C

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.19

 

 

39) A researcher lacked the necessary equipment to measure methane production so instead monitored CO2 concentration as the unknown archaeon grew and produced methane. Why might CO2 NOT decrease but methane still increase?

  1. A) An alternative carbon source such as methanol was used.
  2. B) CO2is not a carbon source used by methanogens.
  3. C) CO2was used an electron donor but not as a carbon substrate.
  4. D) Methanogenic Archaea containing carboxysomes likely made measuring small losses of CO2difficult to conclude.

Answer:  A

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.20

40) Methanogens that use methyl-CoM for biosynthesis use ________ as a substrate.

  1. A) acetate
  2. B) carbon monoxide
  3. C) methane
  4. D) methanol

Answer:  D

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.20

 

41) The serine pathway and ribulose monophosphate pathway can both be used by ________ as a way to incorporate carbon into biomass.

  1. A) acetogens
  2. B) anoxygenic hydrocarbon fermenters
  3. C) methanogens
  4. D) methylotrophs

Answer:  D

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.23

 

42) What products would be expected to form during anoxic degradation of the seven-carbon compound benzoate following reduction and cleavage of the aromatic ring?

  1. A) 1 three-carbon compound and 1 four-carbon compound
  2. B) 1 three-carbon compound and 2 two-carbon compounds
  3. C) 2 three-carbon compounds and CO2
  4. D) 3 two-carbon compounds and CO2

Answer:  B

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.24

 

 

43) Organisms that aerobically catabolize methane use the intermediate ________ for biosynthesis and produce ________ when oxidizing the substrate for energy.

  1. A) CH2O (formaldehyde) / CO
  2. B) CH2O (formaldehyde) / CO2
  3. C) HCOO−(formate) / CO
  4. D) HCOO−(formate) / CO2

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.23

 

44) Which of the following is NOT a potential reason anoxic methane-oxidizing Archaea have not also acquired the ability to reduce sulfate?

  1. A) An individual electron acceptor such as sulfate is not always present where methane is.
  2. B) Minimizing the metabolic requirements of the archaeon’s genome size provides flexibility to interact with other reducing bacteria, such as nitrate reducers.
  3. C) The archaeon-bacterium relationship yields more energy from methane oxidation/sulfate reduction when performed together than separately.
  4. D) The methane-oxidizing Archaea will not easily acquire this metabolic capability from the bacterial partner.

Answer:  C

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.24

45) What metabolism would be favored when there is a lack of electron acceptors?

  1. A) anaerobic fermentation
  2. B) anoxygenic photosynthesis
  3. C) anoxic ammonia oxidation
  4. D) acetogenesis

Answer:  A

Bloom’s Taxonomy:  Evaluation

Chapter Section:  13.11

 

True/False Questions

 

1) The conversion of light into chemical energy is called photoautotrophy.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.1

 

2) The light-harvesting pigments in Bacteria are classified as bacteriochlorophylls.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

 

 

3) Reaction centers ONLY indirectly receive photon energy via light-harvesting molecules.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

 

4) Chlorosomes are present in purple bacteria but absent in green sulfur and nonsulfur bacteria.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.1

 

5) Carotenoids are hydrophobic accessory pigments and vary widely in the color they can absorb.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.2

 

6) Each chlorophyll and bacteriochlorophyll type is distinguished by its absorption spectrum.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.2

 

7) Photooxidation reactions can lead to the production of toxic forms of oxygen and the destruction of the photosynthetic apparatus.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.2

 

8) The Calvin cycle provides autotrophs the ability to convert inorganic carbon into biomass and generate energy during this process.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.5

9) A bacterium that uses CO2 as an electron source but CANNOT use it as a carbon source is considered a mixotroph.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.6

 

10) Phototrophic purple bacteria such as Rhodobacter species grow ONLY by photosynthesis, using bacteriochlorophylls to harvest light.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.3

 

 

11) Despite being called the reverse citric acid cycle, it is currently identified as the most ancient autotrophic pathway.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.5

 

12) Chemolithotrophs that obtain electrons from donors such as sulfide use the same electron transport chains to obtain energy as chemoorganotrophs.

Answer:  TRUE

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.6

 

13) Photosystem I is responsible for splitting a water molecule in the first step of oxygenic electron flow.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.4

 

14) RubisCO converts ribulose bisphosphate and CO2 into two molecules of 3-phosphoglyceric acid (PGA).

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.5

 

15) Organisms grown with CO2 as its sole carbon source must have energy in the form of ATP as well as reducing power.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.1

 

16) Iron-oxidizing bacteria grow better in alkaline environments where protons are less likely to abiotically convert Fe2+ into Fe3+.

Answer:  FALSE

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.9

17) Some sulfur-oxidizing bacteria can simultaneously reduce nitrate, which enables them to grow anaerobically.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.8

 

18) Due to a chemical equilibrium, a syntrophic relationship can be disrupted if the product from the first partner’s metabolism is removed too quickly.

Answer:  FALSE

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.15

 

19) Because H2 levels in oxic environments are transient, it is likely that aerobic hydrogen bacteria shift between chemoorganotrophy and chemolithotrophy depending on levels of organic compounds and hydrogen in their habitats.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.7

 

20) Some anaerobic bacteria not only use organic compounds as a carbon source but can also use them for energy as well.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.11

 

21) Heterofermentation CANNOT be differentiated from homofermentation based on the compound fermented.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.12

 

22) A monooxygenase can always be distinguished from a dioxygenase by incorporating only one oxygen atom from O2 into the substrate rather than both.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.22

 

23) Reductive dechlorination involves chlorinated organic compounds serving as electron donors and releasing the chloride in inorganic forms.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.21

 

24) Fermentation of organic compounds, such as acetate, produces NADH and ATP.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.11

 

25) The acetyl-CoA pathway is a primary route for carbon source utilization.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.18

26) When elemental sulfur is provided externally as an electron donor, the organism must attach itself to the sulfur particle because of the extreme insolubility of elemental sulfur.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  13.8

 

27) One result of the oxidation of reduced sulfur compounds is a rise in the pH of the medium.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.18

 

28) Bacteria that are capable of oxidizing both iron and sulfur usually have a strong preference for sulfur oxidation because it yields more energy.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.9

 

29) Beta-oxidation exclusively removes two carbons at a time to catabolize fatty acids regardless of the carbon chain length.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.22

 

30) Bacteria that degrade aromatic compounds with reductions steps rather than oxygenase activity prior to ring fission are likely to be anaerobes.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.24

 

Essay Questions

 

1) Compare and contrast the prokaryotic and eukaryotic light-gathering machinery function and spatial organization. Why do various chlorophylls show different absorption spectra?

Answer:  Both prokaryotes and eukaryotes use chlorophylls to gather light energy. Eukaryotes have chloroplast organelles that house the chlorophylls. Prokaryotes instead have chlorophylls located within other internal membrane systems. For example, cyanobacteria have thylakoid membranes, and green bacteria have chlorosomes. Different chlorophylls (e.g., Chl a and Chl b) have structural variations at the chemical level, which results in varied capabilities of absorbing different light wavelengths. Consequently, the light that these various chlorophylls absorb also make them transmit (or appear) as different colors too.

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.1

 

2) What is the difference between chlorophyll and bacteriochlorophyll, and which organisms contain each?

Answer:  Chlorophylls are used in phototrophs where oxygen is released and can be present in bacteria in addition to eukaryotes. Bacteriochlorophylls are found only in anoxic phototrophs such as purple bacteria and are not present in eukaryotes.

Bloom’s Taxonomy:  Analysis

Chapter Section:  13.1

 

3) Explain the Calvin cycle process that produces a full molecule of glucose and regenerates the ribulose bisphosphate molecule.

Answer:  It takes 6 CO2 and 6 ribulose bisphosphate molecules to go through the Calvin cycle to generate 1 glucose molecule. The first main step in the cycle involves RubisCO creating 3-phosphoglyceric acid (PGA) from CO2 and ribulose-1,5 bisphosphate. ATP and NADPH are then used to convert PGA into glyceraldehyde-3-phosphate (G3P). Finally, ribulose biphosphate is regenerated from G3P. Ultimately, 12 NADPH and 18 ATP are required to synthesize one glucose molecule.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.4

 

4) In what types of organisms are carboxysomes found and what advantage do they provide for a cell?

Answer:  Many prokaryotic autotrophs create inclusions within their cells that harbor large quantities of RubisCO. They are especially advantageous for cells to ensure carboxylation of ribulose-1,5 bisphosphate via RubisCO occurs (for carbon assimilation) rather than oxygenation, which requires additional energy input.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.5

 

5) Describe what occurs when elemental sulfur is provided externally as an electron donor and how energy is obtained.

Answer:  Elemental sulfur (S0) can serve as an electron donor for colorless sulfur bacteria. Aerobic chemolithotrophy of S0 uses elemental sulfur, oxygen, and water to form sulfate ions. The reduced sulfates can then enter the electron transport chain to produce a proton motive force, ultimately driving the production of energy in the form of ATP.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.8

 

6) Illustrate the reaction center of a purple bacterium with the following features highlighted: antenna pigments, the special pair, protein H, protein L, protein M, quinone pool, and ATPase. Also explain the importance of proximity for these components within a reaction center.

Answer:  The illustration should follow what is outlined in Figures 13.4a, 13.11b, and 13.12b in the textbook. Several morphologies exist, and the overall diagram should indicate their relative close proximity to each other so that electron transfer can occur at a fast rate.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.3

 

7) Explain why it is unlikely an iron-oxidizing bacterium would thrive in a cold stream with a neutral pH. Also propose an experiment that would test whether iron-oxidizing bacteria are present in the stream.

Answer:  In an oxic environment, such as a stream, the iron present in the water will be primarily Fe3+. Iron-oxidizing bacteria require Fe2+ as an electron source, and this form of iron spontaneously oxidizes into Fe3+ by oxygen. Due to such low bioavailability of the necessary Fe2+, it would be unlikely iron-oxidizing bacteria would exist in such a system. Experimental approaches will vary but must make clear measuring loss of Fe2+ supplemented into the stream water is insufficient evidence of microbial transformation. Iron-oxidizing bacteria could be identified in the stream water by classical enrichment approaches and acidifying the stream water to minimize abiotic iron oxidation. Concomitant growth of an isolate with ferric iron precipitation would be strong evidence such bacteria do occur in the stream.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.9

 

8) Propose why it would be advantageous for a photosynthetic microorganism to have more than one type of chlorophyll or bacteriochlorophyll.

Answer:  Each type of chlorophyll or bacteriochlorophyll absorbs different wavelengths of light, so additional types of chlorophyll can take advantage of more photons to produce even more energy.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.2

 

9) Under what circumstances does oxygenic photophosphorylation use non-cyclic photophosphorylation and when does it use cyclic photophosphorylation? Also describe what occurs during each process.

Answer:  Oxygenic photosynthesis generates ATP via ATPase from a proton motive force, created by electron transport. Electrons are used to reduce NADP+ and form NADPH (reducing power); thus electrons are not cycled. When sufficient quantities of NADPH are made, electrons are used to cycle through the electron transport chain, and P680 (PSII) is re-reduced. During cyclic photophosphorylation, electrons are transferred in a closed system where there is no consumption or input of electrons. NADPH is not made; instead, additional ATP is synthesized from the added proton motive force generated.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  13.3

 

10) Why does an organism that is able to respire both aerobically and anaerobically preferentially undergo aerobic respiration?

Answer:  Oxygen as the terminal electron acceptor is preferred over other molecules, because aerobic respiration yields more energy. The glucose produced by aerobes can be directly used as a carbon source, whereas anaerobes use additional energy in the Calvin cycle to obtain a carbon source.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.16

 

11) Explain why most iron-oxidizing bacteria are obligately acidophilic, and discuss some of the environments where these organisms are found.

Answer:  Oxidation of iron at a low pH does not create high yields of energy. However, to compensate for the oxidation of iron, a reduction must also occur to balance the reaction. At a low pH, protons can be subsequently reduced. Bacteria with this metabolic capacity are prevalent in acid-polluted and coal-mining environments.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.9

 

12) Explain why the discovery of iron-oxidizing phototrophs has important implications for both understanding the evolution of photosynthesis and explaining the large deposits of ferric iron (Fe3+) found in ancient sediments on Earth.

Answer:  The sediments containing Fe3+ predate the existence of photosynthetic cyanobacteria that were responsible for oxygenation of the Earth. It is therefore likely these Fe3+ deposits were not formed through spontaneous (abiotic) conversion of Fe2+ and O2. Instead, it is thought anaerobic chemolithotrophs or anoxygenic phototrophs created these deposits through oxidation of Fe2+ into Fe3+.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  13.10

Brock Biology of Microorganisms, 14e (Madigan et al.)

Chapter 23  Microbial Interactions with Humans

 

Multiple Choice Questions

 

1) Pathogenicity is the ability

  1. A) of the host to inflict damage on the pathogen.
  2. B) of the host to resist damage by the pathogen.
  3. C) of the pathogen to inflict damage on the host.
  4. D) None of these are correct.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

2) Which of the following is NOT a subunit of lipopolysaccharide (LPS)?

  1. A) O-specific polysaccharide
  2. B) lipid A
  3. C) core polysaccharide
  4. D) M protein

Answer:  D

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.10

 

3) One microenvironment of the skin is an area where glands produce an oily substance called

  1. A) mucus.
  2. B) sebum.
  3. C) fimbrae.
  4. D) lipid A.

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.2

 

4) Following antibiotic therapy, patients are often administered ________ to facilitate recolonizaton of normal flora.

  1. A) fluoride
  2. B) iron
  3. C) probiotics
  4. D) antivirals

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.4

 

 

5) Decalcification of the tooth enamel due to the production of high concentrations of organic acids in the mouth is known as

  1. A) degenerative plaque.
  2. B) dental caries.
  3. C) dental plaque.
  4. D) microbial enamel decalcification.

Answer:  D

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.8

6) The following bacterial species are all implicated in dental caries EXCEPT

  1. A) Fusobacterium.
  2. B) Borrelia.
  3. C) Streptococcus.
  4. D) Lactobacillus.

Answer:  D

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.8

 

7) Which of these microorganisms is MOST likely to be found in the human gut?

  1. A) Helicobacter pylori
  2. B) Streptococcus sobrinus
  3. C) Streptococcus mutans
  4. D) Roseobacter denitrificans

Answer:  A

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.4

 

8) Normal flora in the duodenum are

  1. A) similar to the microflora in the stomach.
  2. B) dominated by aerobic organisms.
  3. C) tolerant to alkaline environments.
  4. D) tolerant to high salinity.

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.4

 

9) Which of the following are NOT found in the gastrointestinal tract of healthy humans?

  1. A) Bacteroides
  2. B) Clostridium
  3. C) Escherichia coli
  4. D) protists

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.4

 

 

10) The following compounds are all produced by intestinal microflora EXCEPT

  1. A) flatus.
  2. B) vitamin C.
  3. C) vitamin B12.
  4. D) vitamin K.

Answer:  B

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.4

11) Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells.

  1. A) collagenase
  2. B) coagulase
  3. C) lipase
  4. D) amylase

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.8

 

12) Only particles smaller than ________ µm in diameter reach the lungs.

  1. A) 10
  2. B) 20
  3. C) 30
  4. D) 40

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.5

 

13) The vagina of adult female is

  1. A) highly acidic.
  2. B) highly alkaline.
  3. C) weakly acidic.
  4. D) weakly alkaline.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.5

 

14) Which of the following hemolysins is a phospholipase?

  1. A) lecithinase
  2. B) Streptolysin-O
  3. C) Staphylococcal -toxin
  4. D) leukocidin

Answer:  A

Bloom’s Taxonomy:  Evaluation

Chapter Section:  23.8

 

 

15) Streptocoocus pyogens utilizes M protein and ________ to form microfibrils that facilitate attachment to host cells.

  1. A) lipoteichoic acid
  2. B) mucus
  3. C) plaque
  4. D) None of the answers are correct.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.7

16) Influenza virus targets

  1. A) respiratory epithelium.
  2. B) gastrointestinal cells.
  3. C) oral cavity cells.
  4. D) throat epithelium.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.11

 

17) A polymer coat consisting of a dense, well-defined polymer layer surrounding a cell is called a

  1. A) capsule.
  2. B) glycocalyx.
  3. C) lipopolysaccharide.
  4. D) slime mold.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

18) Capsules are particularly important for

  1. A) making bacteria more vulnerable to host defense mechanisms.
  2. B) making bacteria less pathogenic.
  3. C) protecting bacteria from host defense mechanisms.
  4. D) allowing bacteria to become more phagocytic.

Answer:  C

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.6

 

19) The decrease or loss of virulence of a pathogen is referred to as

  1. A) aging.
  2. B) attenuation.
  3. C) disinfectivity.
  4. D) lethal dose.

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

20) Attenuation occurs in a laboratory, because

  1. A) nonvirulent or weakly virulent mutants grow faster in vitro in laboratory media.
  2. B) pathogens lose virulence with age.
  3. C) patients are generally treated with drugs that induce attenuation.
  4. D) None of the answers are correct.

Answer:  A

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.6

21) Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen?

  1. A) malaria
  2. B) measles
  3. C) mumps
  4. D) rubella

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

22) Which of the following is NOT important for the adherence of bacteria to other bacteria as well as to host tissue?

  1. A) adherence polymers
  2. B) capsule
  3. C) glycocalyx
  4. D) slime layer

Answer:  A

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.6

 

23) Which of the following is an important factor in the development of dental caries?

  1. A) high salt diet
  2. B) high sugar diet
  3. C) high acid diet
  4. D) low salt diet

Answer:  B

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.12

 

24) The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called

  1. A) bacteremia.
  2. B) cancer.
  3. C) pathogenesis.
  4. D) septicemia.

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.7

 

25) Which genus produces hyaluronidase?

  1. A) Mycobacteria
  2. B) Streptococcus
  3. C) Shigella
  4. D) Procholorococcus

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.8

26) Which of the following is more likely to cause urinary tract infections?

  1. A) fimbriated strains of Escherichia coli
  2. B) non-fimbriated strains of Escherichia coli
  3. C) both fimbriated and non-fimbriated strains of Escherichia coli
  4. D) None of the answers are correct.

Answer:  A

Bloom’s Taxonomy:  Evaluation

Chapter Section:  23.6

 

27) Pathogenic strains of Escherichia coli usually express

  1. A) capsules.
  2. B) colonization factor antigens (CFA).
  3. C) plaques.
  4. D) slime layers.

Answer:  B

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.7

 

28) Which of the following does NOT affect pathogen growth?

  1. A) availability of microbial nutrients
  2. B) pH
  3. C) temperature
  4. D) doubling time

Answer:  D

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.1

 

29) Siderophores from some pathogens remove iron from the host protein(s)

  1. A) lactoferrin.
  2. B) transferrin.
  3. C) both lactoferrin and transferrin.
  4. D) cytochromes.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.8

 

 

30) Cytolytic toxins

  1. A) are extracellular proteins.
  2. B) cause cell lysis and death.
  3. C) damage host cytoplasmic membrane.
  4. D) are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

Answer:  D

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.9

31) Normal flora ________ colonization of pathogenic organisms.

  1. A) promote
  2. B) prevent
  3. C) maintain
  4. D) accelerate

Answer:  B

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.11

 

32) The collective term for the organisms living on or in the human body is

  1. A) normal microbial flora.
  2. B) fomite flora.
  3. C) transient microbial flora.
  4. D) pathogenic flora.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.1

 

33) ________ in saliva cleaves glycosidic linkages in peptidoglycan present in bacterial cell walls, weakening the wall and causing cell lysis.

  1. A) Mucus
  2. B) Lysozyme
  3. C) Fibrin
  4. D) Lipid A

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.3

 

34) Which of the following is a way to prevent attenuation and maintain virulence in a bacterium?

  1. A) laboratory subculture
  2. B) animal passage
  3. C) polymerase chain reaction (PCR)
  4. D) antibiotic therapy

Answer:  B

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.6

 

35) The human gastrointestinal tract includes all of the following EXCEPT the

  1. A) small intestine.
  2. B) stomach.
  3. C) large intestine.
  4. D) epiglottis.

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.4

36) A(n) ________ is a damage or injury to a host organism that impairs its function.

  1. A) trauma
  2. B) infection
  3. C) disease
  4. D) transmission

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

37) Virulence is the relative ability of a ________ to cause disease.

  1. A) pathogen
  2. B) commensal
  3. C) virus
  4. D) bacterium

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

38) Which of the following is the dominate genera of skin microflora?

  1. A) Bacteriodes
  2. B) Firmicutes
  3. C) Actinobacteria
  4. D) Proteobacteria

Answer:  C

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.2

 

39) Which of the following environmental and host factors influence the composition of resident microflora on the skin?

  1. A) age
  2. B) personal hygiene
  3. C) weather
  4. D) age, personal hygiene, and weather

Answer:  D

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.2

 

40) Extensive growth of the streptococci in a thick bacterial layer on acidic glycoproteins on the teeth is called

  1. A) dental plaque.
  2. B) dental caries.
  3. C) dental biofilm.
  4. D) periodontitis.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.8

41) Which of the following pathogens does NOT require capsules or a slime layer for attachment?

  1. A) Vibrio cholera
  2. B) Streptococcus pneumonia
  3. C) Bacillus anthracis
  4. D) All of these pathogens require capsules or slime layers for attachment.

Answer:  A

Bloom’s Taxonomy:  Evaluation

Chapter Section:  23.7

 

42) Which of the following is a major growth-limiting micronutrient that influences microbial growth?

  1. A) iron
  2. B) transferrin
  3. C) lactoferrin
  4. D) sugar

Answer:  A

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.8

 

43) The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

  1. A) Antigen dose50.
  2. B) Virulence-50.
  3. C) LD50 (lethal dose50).
  4. D) Death rate-50.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

 

44) The process by which microorganisms cause diseases is known as

  1. A) pathogenesis.
  2. B) virulence.
  3. C) LD50 (lethal dose50).
  4. D) infection.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

45) The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called

  1. A) lipid A.
  2. B) biofilms.
  3. C) capsules.
  4. D) glycocalyx.

Answer:  D

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

46) A loose network of polymers extending outward from a cell is called a(n)

  1. A) slime layer.
  2. B) lipid A.
  3. C) capsule.
  4. D) adhesion.

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

47) The process by which white blood cells ingest and kill bacteria is called

  1. A) exocytosis.
  2. B) transcription.
  3. C) phagocytosis.
  4. D) translation.

Answer:  C

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.7

 

48) The condition that results when some organisms are shed in the bloodstream and distributed to distant parts of the body during bacterial growth in tissues is called

  1. A) septicemia.
  2. B) bacteremia.
  3. C) uremia.
  4. D) erythemia.

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.7

 

49) ________ are toxic proteins released from the pathogen as it grows.

  1. A) Endotoxins
  2. B) Exotoxins
  3. C) Macrotoxins
  4. D) Microtoxins

Answer:  B

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.9

 

50) Which of the following is a category of exotoxin?

  1. A) cytolytic toxin
  2. B) lipophilic toxin
  3. C) α-toxin
  4. D) β-toxin

Answer:  A

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.9

51) ________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts.

  1. A) Healthcare-associated infections
  2. B) Immunocompromised infections
  3. C) Pathogenic infections
  4. D) Virulent infections

Answer:  A

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.12

 

True/False Questions

 

1) ALL microorganisms that live in the human body are harmful.

Answer:  FALSE

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.1

 

2) Bacteria found in the mouth in the first years of life are well-adapted to biofilm formation.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.3

 

3) An opportunistic pathogen causes disease ONLY in the presence of normal host resistance.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.6

 

 

4) Normal microflora are usually found in the blood, lymph, and nervous systems of the body.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.1

 

5) Virulence refers to the ability of an organism to cause disease.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

6) Streptococcus mutans can produce dextran when sucrose is present in the absence of the enzyme dextransucrase.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.12

 

7) Pathogen virulence NEVER changes throughout a host’s life.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.6

 

8) Cholera begins following a bite from a mosquito.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.9

9) Protists are NOT normally found in the gastrointestinal tract of healthy individuals.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.9

 

10) Bacteria make up about one-third the weight of fecal matter.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.4

 

11) Malassezia spp. are the MOST common fungi present on the skin of humans.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.2

 

12) The upper respiratory tract usually has a considerable amount of resident microflora in a healthy adult.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.5

 

13) Vaginal acidity in the adult female is due to acid production by Lactobacillus acidophilus.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.5

 

14) R plasmids help prevent the spread of virulence factors.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.8

 

15) Invasion is the ability of a pathogen to enter into host cells or tissues, spread, and cause disease.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.6

 

16) The toxic lipopolysaccharides produced by MOST gram-negative bacteria are called exotoxins.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.10

 

17) Endotoxins are released in large amounts only when cells lyse.

Answer:  TRUE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.10

 

18) The Limulus amebocyte lysate assay is used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.10

19) Gram-positive bacteria produce endotoxins.

Answer:  FALSE

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.10

 

20) Hormones that are produced under stress boost normal immune responses and play a role in stress-mediated disease resistance.

Answer:  FALSE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.12

 

 

21) The number of Vibrio cholera cells necessary to produce cholera in an exposed individual is drastically reduced if the individual is malnourished.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.12

 

22) Clostridium botulinum are endospore-forming bacteria normally found in the soil.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.9

 

23) Animals that lack CXCR4 and CCR5 proteins are immune to HIV infection.

Answer:  TRUE

Bloom’s Taxonomy:  Evaluation

Chapter Section:  23.11

 

24) Diphtheria toxin inactivates elongation factor 2 by catalyzing the attachment of adenosine diphosphate ribose from NAD+.

Answer:  TRUE

Bloom’s Taxonomy:  Knowledge

Chapter Section:  23.9

 

25) Clostridium botulinum cannot produce toxins in improperly preserved foods.

Answer:  FALSE

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.9

 

Essay Questions

 

1) Explain how diet plays a role in host susceptibility to infection.

Answer:  Diet alters the normal flora, allowing opportunistic pathogens a better chance of multiplying and increasing the overall susceptibility of the host to known pathogens. Also, the presence of a particular substance in the diet can trigger disease. For example, Streptococcus mutans can only produce dextran in the presence of sucrose (leading to attachment of the bacteria and dental caries).

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.12

2) Why are some microorganisms specialized to only certain parts of the body? Describe an example that supports your answer.

Answer:  Each organ differs chemically and physically from others and thus provides a selective environment for the growth of certain microorganisms. Examples will vary.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.1

 

 

3) When does an infection become a disease?

Answer:  An infection becomes a disease when a microorganism that is established and growing in a host causes damage and injury that impairs host function.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.6

 

4) Design an experiment to determine whether a potential pathogen produces hemolysins.

Answer:  Bacterial production of hemolysins is demonstrated in the laboratory by streaking the pathogen on blood agar plates containing 5% sheep’s blood. If hemolysins are produced and released, red blood cell lysis will occur, releasing hemoglobin and creating a clear area called a zone of hemolysis around the growing colonies.

Bloom’s Taxonomy:  Synthesis

Chapter Section:  23.9

 

5) How do dental lactic acid bacteria cause dental caries?

Answer:  Lactic acid bacteria ferment sugars in the diet to lactic acid that dissolves some of the calcium phosphate in localized areas, and the proteolysis of the supporting matrix occurs through the action of bacterial proteoloytic enzymes. Bacterial cells slowly penetrate into the decomposing matrix.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.8

 

6) Describe how orally taken antibiotics can result in the harmful alteration in digestive functions and disease.

Answer:  Antibiotics inhibit the growth of the normal flora as well as pathogens leading to the loss of antibiotic-susceptible bacteria in the intestinal tract. In the absence of the full complement of normal flora, opportunistic microorganisms such as Candida ablibacans can become established.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.4

 

7) What is the similarity between the flora found in a female at the menopause stage and a female at the pre-puberty stage? How different is it from a female between the stages of puberty and menopause?

Answer:  The flora in both cases lack Lactobacillus acidophilus because the female genitals do not produce glycogen at these stages, therefore there is no need to convert glycogen to lactic acid to keep the pH of the genitals slightly acidic. The pH is thus higher than that of females between the stages of puberty and menopause.

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.5

8) Why does Neisseria gonorrhea adhere only to mucosal epithelial cells in the genitourinary tract, eye, rectum, and throat?

Answer:  N. gonorrhea has a surface protein called Opa (opacity associated protein) that binds specifically to a host protein called CD66 that is found only on the surfaces of these cells.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.7

 

9) What is the difference between pathogenic and non-pathogenic E. coli in relation to the human host?

Answer:  Most nonpathogenic E. coli strains are found in the cecum and colon and routinely pass through the body through the feces without causing disease. Pathogenic enterotoxigenic strains of E. coli contain genes encoding fimbrial colonization factor antigens, leading to bacterial adherence in the host small intestine. These bacteria produce enterotoxins, leading to diarrhea.

Bloom’s Taxonomy:  Evaluation

Chapter Section:  23.7

 

10) Explain how Clostridium tetani cells that rarely leave their initial site of infection can cause death in their hosts.

Answer:  C. tetani produces tetanus toxins that move to distant parts of the body, initiating irreversible muscle contraction, and often death of the host. Although the cells do not actively travel around the host, the toxins it produces cause the death of the host.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.9

 

11) Describe the difference between the use of streptokinase and coagulase as a defense mechanism among pathogens.

Answer:  Pathogens like Streptococcus pyogens use streptokinase as a fibrinolytic enzyme that dissolves fibrin clots, which makes invasion of pathogens impossible by localizing their infection. On the other hand, coagulase is used by pathogens like Staphylococcus aureus to form and insoluble fibrin layer around them, thus protecting themselves from attack from host cells.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.8

 

12) What are the different categories of exotoxins, and how do they function?

Answer:  The three categories are AB toxins, cytolytic toxins, and superantigen toxins. The cytolytic toxins work by degrading cytoplasmic membrane integrity causing lysis. The superantigens work by stimulating large numbers of immune cells resulting in extensive inflammation and tissue damage. The AB toxins bind to host cell surface receptors and damage the cell when the A subunit is transferred across the targeted cytoplasmic membrane by the B subunit.

Bloom’s Taxonomy:  Analysis

Chapter Section:  23.9

 

13) Why is fever the universal result of endotoxin exposure?

Answer:  Endotoxins stimulate host cells to release cytokines that act as proteins that affect the temperature-controlling center of the brain, causing fever.

Bloom’s Taxonomy:  Comprehension

Chapter Section:  23.10

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