Chapter 5

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Microbiology
Chapter 5
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1

1) Which of the following compounds is NOT an enzyme?

A) dehydrogenase

B) cellulase

C) coenzyme A

D) β-galactosidase

E) sucrase

Answer: C

2
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2) Figure 5.1

Which compound is being reduced in the reaction shown in Figure 5.1?

A) isocitric acid and α-ketoglutaric acid

B) α-ketoglutaric acid and NAD+

C) NAD+

D) NADH

E) NADH and isocitric acid

Answer: C

3

3) Which organism is NOT correctly matched to its energy source?

A) photoheterotroph - light

B) photoautotroph - CO2

C) chemoautotroph - Fe2+

D) chemoheterotroph - glucose

E) chemoautotroph-NH3

Answer: B

4

4) Which of the following statements about anaerobic respiration is FALSE?

A) It yields lower amounts of ATP when compared to aerobic respiration.

B) The complete Kreb's cycle is utilized.

C) It involves the reduction of an organic final electron acceptor.

D) It generates ATP.

E) It requires cytochromes.

Answer: C

5
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What type of reaction is in Figure 5.2?

A) decarboxylation

B) transamination

C) dehydrogenation

D) oxidation

E) reduction

Answer: B

6

6) What is the fate of pyruvic acid in an organism that uses aerobic respiration?

A) It is reduced to lactic acid.

B) It reacts with oxaloacetate to form citrate.

C) It is oxidized in the electron transport chain.

D) It is catabolized in glycolysis.

E) It is converted into acetyl CoA.

Answer: E

7
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How would a noncompetitive inhibitor interfere with a reaction involving the enzyme shown in Figure 5.3?

A) It would bind to a.

B) It would bind to b.

C) It would bind to c.

D) It would bind to d.

E) The answer cannot be determined based on the information provided.

Answer: B

8
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How is ATP generated in the reaction shown in Figure 5.4?

A) glycolysis

B) fermentation

C) photophosphorylation

D) oxidative phosphorylation

E) substrate-level phosphorylation

Answer: E

9

9) Fatty acids are oxidized in

A) the Krebs cycle.

B) the electron transport chain.

C) glycolysis.

D) the pentose phosphate pathway.

E) the Entner-Doudoroff pathway.

Answer: A

10
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Which of the graphs in Figure 5.5 best illustrates the activity of an enzyme that is saturated with substrate?

A) a

B) b

C) c

D) d

E) e

Answer: C

11

11) Which of the following is the best definition of oxidative phosphorylation?

A) Electrons are passed through a series of carriers to O2.

B) A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.

C) ATP is directly transferred from a substrate to ADP.

D) Electrons are passed through a series of carriers to an organic compound.

Answer: B

12

12) Which of the following statements about substrate-level phosphorylation is FALSE?

A) It involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP.

B) No final electron acceptor is required.

C) It occurs in glycolysis.

D) The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.

E) It occurs to a lesser degree in the Krebs cycle than in glycolysis.

Answer: D

13

13) Which of the following statements about photophosphorylation is FALSE?

A) Light liberates an electron from chlorophyll.

B) The oxidation of carrier molecules releases energy.

C) Energy from oxidation reactions is used to generate ATP from ADP.

D) It requires CO2.

E) It occurs in photosynthesizing cells.

Answer: D

14

14) A strictly fermentative bacterium produces energy

A) by glycolysis only.

B) by aerobic respiration only.

C) by fermentation or aerobic respiration.

D) only in the absence of oxygen.

E) only in the presence of oxygen.

Answer: A

15

15) The advantage of the pentose phosphate pathway is that it produces all of the following EXCEPT

A) precursors for nucleic acids.

B) precursors for the synthesis of glucose.

C) three ATPs.

D) NADPH.

E) precursors for the synthesis of amino acids.

Answer: C

16

16) Which biochemical process is NOT used during glycolysis?

A) substrate-level phosphorylation

B) oxidation-reduction

C) carbohydrate catabolism

D) beta oxidation

E) enzymatic reactions

Answer: D

17

17) In noncyclic photophosphorylation, O2 is released from

A) CO2.

B) H2

C) C6H12O6.

D) sunlight.

E) chlorophyll.

Answer: B

18

18) Which of the following is the best definition of fermentation?

A) the partial reduction of glucose to pyruvic acid

B) the partial oxidation of glucose with organic molecules serving as electron acceptors

C) the complete catabolism of glucose to CO2and H2O

D) the production of energy by oxidative-level phosphorylation

E) the production of energy by both substrate and oxidative phosphorylation

Answer: B

19

19) Which of the following is NOT necessary for respiration?

A) cytochromes

B) flavoproteins

C) a source of electrons

D) oxygen

E) quinones

Answer: D

20

20) Which one of the following would you predict is an allosteric inhibitor of the Krebs cycle enzyme, α-ketoglutarate dehydrogenase?

A) citric acid

B) α-ketoglutaric acid

C) NAD+

D) NADH

E) ADP

Answer: D

21

21) In green and purple bacteria, electrons to reduce CO2 can come from

A) CO2.

B) H2

C) C6H12O6.

D) H2

E) chlorophyll.

Answer: D

22

22) Assume you are growing bacteria on a lipid medium that started at pH 7. The action of bacterial lipases should cause the pH of the medium to

A) increase.

B) decrease.

C) stay the same.

Answer: B

23

23) Which of the following uses CO2 for carbon and H2 for energy?

A) chemoautotroph

B) chemoheterotroph

C) photoautotroph

D) photoheterotroph

Answer: A

24

24) Which of the following uses glucose for carbon and energy?

A) chemoautotroph

B) chemoheterotroph

C) photoautotroph

D) photoheterotroph

Answer: B

25

25) Which of the following has bacteriochlorophylls and uses alcohols for carbon?

A) chemoautotroph

B) chemoheterotroph

C) photoautotroph

D) photoheterotroph

Answer: D

26

26) Cyanobacteria are a type of

A) chemoautotroph.

B) chemoheterotroph.

C) photoautotroph.

D) photoheterotroph.

Answer: C

27

27) Which of the following statements are TRUE?

1-Electron carriers are located at ribosomes.

2-ATP is a common intermediate between catabolic and anabolic pathways.

3-ATP is used for the long-term storage of energy and so is often found in storage granules.

4-Anaerobic organisms are capable of generating ATP via respiration.

5-ATP can be generated by the flow of protons across protein channels.

A) 2, 4, 5

B) 1, 3, 4

C) 2, 3, 5

D) 1, 2, 3

E) All of the statements are true.

Answer: A

28

28) Microorganisms that catabolize sugars into ethanol and hydrogen gas would most likely be categorized as

A) aerobic respirers.

B) anaerobic respirers.

C) heterolactic fermenters.

D) homolactic fermenters.

E) alcohol fermenters.

Answer: C

29

29) Which of the following statements regarding metabolism is FALSE?

A) Heat may be released in both anabolic and catabolic reactions.

B) ATP is formed in catabolic reactions.

C) ADP is formed in anabolic reactions.

D) Anabolic reactions are degradative.

Answer: D

30
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30) Which of the following is TRUE about this reaction?

A) This process requires O2.

B) This process occurs anaerobically.

C) This process requires the entire electron transport system.

D) This process requires light.

E) This process requires O2and the electron transport system.

Answer: B

31

31) Which of the following statements regarding the Entner-Doudoroff pathway is TRUE?

A) It involves glycolysis.

B) It involves the pentose phosphate pathway.

C) NADH is generated.

D) ATP is generated.

E) NADH and ATP are generated.

Answer: D

32

32) Assume you are working for a chemical company and are responsible for growing a yeast culture that produces ethanol. The yeasts are growing well on the maltose medium but are not producing alcohol. What is the most likely explanation?

A) The maltose is toxic.

B) O2is in the medium.

C) Not enough protein is provided.

D) The temperature is too low.

E) The temperature is too high.

Answer: B

33
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The rates of O2 and glucose consumption by a bacterial culture are shown in Figure 5.6. Assume a bacterial culture was grown in a glucose medium without O2. Then O2 was added at the time marked X. The data indicate that

A) these bacteria don't use O2.

B) these bacteria get more energy anaerobically.

C) aerobic metabolism is more efficient than fermentation.

D) these bacteria cannot grow anaerobically.

Answer: C

34

34) An enzyme, citrate synthase, in the Krebs cycle is inhibited by ATP. This is an example of all of the following EXCEPT

A) allosteric inhibition.

B) competitive inhibition.

C) feedback inhibition.

D) noncompetitive inhibition.

Answer: B

35

35) If a cell is starved for ATP, which of the following pathways would most likely be shut down?

A) Kreb's cycle

B) glycolysis

C) pentose phosphate pathway

D) Krebs cycle and glycolysis

Answer: C

36

36) Which of the following statements regarding the glycolysis pathway is FALSE?

A) Two pyruvate molecules are generated.

B) Four ATP molecules are generated via substrate-level phosphorylation.

C) Two NADH molecules are generated.

D) One molecule of ATP is expended.

E) Two molecules of water are generated.

Answer: D

37
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The graph at the left in Figure 5.7 shows the reaction rate for an enzyme at its optimum temperature. Which graph shows enzyme activity at a higher temperature?

A) a

B) b

C) c

D) d

Answer: B

38

38) A bacterial culture grown in a glucose-peptide medium causes the pH to increase. The bacteria are most likely

A) fermenting the glucose.

B) oxidizing the glucose.

C) using the peptides.

D) not growing.

Answer: C

39

39) Gallionella bacteria can get energy from the reaction Fe2+ → Fe3+. This reaction is an example of

A) oxidation.

B) reduction.

C) fermentation.

D) photophosphorylation.

E) the Calvin-Benson cycle.

Answer: A

40
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40) In Figure 5.8, where is ATP produced?

A) a

B) b

C) c

D) d

E) e

Answer: E

41
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41) Refer to Figure 5.8. In aerobic respiration, where is water formed?

A) a

B) b

C) c

D) d

E) e

Answer: D

42
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42) In Figure 5.8, the structure labeled "1" is
A) NAD+.
B) ATP synthase.
C) a plasma membrane.
D) a cell wall.
E) cytoplasm.

Answer: C

43
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43) In Figure 5.8, the path labeled "2" is the flow of

A) electrons.

B) protons.

C) energy.

D) water.

E) glucose.

Answer: B

44
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44) What is the most acidic place in Figure 5.8?

A) a

B) b

C) c

D) d

E) e

Answer: A

45

45) A urease test is used to identify Mycobacterium tuberculosis because

A) urease is a sign of tuberculosis.

B) tuberculosis produces urease.

C) urea accumulates during tuberculosis.

D) some bacteria reduce nitrate ion.

E) bovis can cause tuberculosis.

Answer: B

46

46) Researchers are developing a ribozyme that cleaves the HIV genome. This pharmaceutical agent could be described as

A) an RNA molecule capable of catalysis.

B) a hydrolase.

C) a genetic transposable element.

D) a protease inhibitor.

E) a competitive inhibitor for reverse transcriptase.

Answer: A

47

47) Which statements correspond to amphibolic pathways?

  1. anabolic and catabolic reactions are joined through common intermediate
  2. shared metabolic pathways
  3. Feedback inhibition can help regulate rates of reactions
  4. both types of reactions are necessary but do not occur simultaneously

A) 1 only

B) 1, 2, 3

C) 1, 2, 3, 4

D) 2, 4

E) 2, 3, 4

Answer: B