Deck 5: Microbial Metabolism

Question 1

Figure 5.2 What type of reaction is in Figure 5.2?

A) decarboxylation
B) dehydrogenation
C) oxidation
D) reduction
E) transamination

Answer 1

E

Question 2

Which of the following is the best definition of fermentation?

A) the production of energy by oxidative-level phosphorylation
B) the complete catabolism of glucose to CO₂ and H₂O
C) the production of energy by both substrate and oxidative phosphorylation
D) the partial oxidation of glucose with organic molecules serving as electron acceptors
E) the partial reduction of glucose to pyruvic acid

Answer 2

D

Question 3

Which of the following compounds is NOT an enzyme?

A) dehydrogenase
B) sucrase
C) cellulase
D) β-galactosidase
E) coenzyme A

Answer 3

E

Question 4

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 amino acids.
C) three ATPs.
D) NADPH.
E) precursors for the synthesis of glucose.

Question 5

Figure 5.5 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

Question 6

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

A) It is oxidized in the electron transport chain.
B) It is reduced to lactic acid.
C) It is catabolized in glycolysis.
D) It reacts with oxaloacetate to form citrate.
E) It is converted into acetyl CoA.

Question 7

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

A) α-ketoglutaric acid and NAD+
B) NADH and isocitric acid
C) NADH
D) isocitric acid and α-ketoglutaric acid
E) NAD+

Question 8

Which of the following statements about photophosphorylation is FALSE?

A) Light liberates an electron from chlorophyll.
B) It occurs in photosynthesizing cells.
C) It requires CO₂.
D) The oxidation of carrier molecules releases energy.
E) Energy from oxidation reactions is used to generate ATP from ADP.

Question 9

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

A) glycolysis
B) oxidative phosphorylation
C) photophosphorylation
D) fermentation
E) substrate-level phosphorylation

Question 10

Which organism is NOT correctly matched to its energy source?

A) chemoheterotroph - glucose
B) photoheterotroph - light
C) photoautotroph - CO₂
D) chemoautotroph - Fe₂+
E) chemoautotroph-NH₃

Question 11

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

A) It occurs in glycolysis.
B) It involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP.
C) No final electron acceptor is required.
D) It occurs to a lesser degree in the Krebs cycle than in glycolysis.
E) The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.

Question 12

Which of the following is NOT necessary for respiration?

A) cytochromes
B) a source of electrons
C) quinones
D) flavoproteins
E) oxygen

Question 13

In noncyclic photophosphorylation, O₂ is released from

A) H₂O.
B) sunlight.
C) C6H12O6.
D) chlorophyll.
E) CO₂.

Question 14

Which of the following statements about anaerobic respiration is FALSE?

A) It requires cytochromes.
B) The complete Krebʹs cycle is utilized.
C) It yields lower amounts of ATP when compared to aerobic respiration.
D) It involves the reduction of an organic final electron acceptor.
E) It generates ATP.

Question 15

Fatty acids are oxidized in

A) the Krebs cycle.
B) the Entner-Doudoroff pathway.
C) the pentose phosphate pathway.
D) the electron transport chain.
E) glycolysis.

Question 16

Figure 5.3 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.

Question 17

Which biochemical process is NOT used during glycolysis?

A) substrate-level phosphorylation
B) beta oxidation
C) oxidation-reduction
D) carbohydrate catabolism
E) enzymatic reactions

Question 18

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

A) A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.
B) Electrons are passed through a series of carriers to an organic compound.
C) Electrons are passed through a series of carriers to O₂.
D) ATP is directly transferred from a substrate to ADP.

Question 19

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

A) ADP
B) α-ketoglutaric acid
C) NAD+
D) NADH
E) citric acid

Question 20

A strictly fermentative bacterium produces energy

A) only in the presence of oxygen.
B) by aerobic respiration only.
C) by fermentation or aerobic respiration.
D) only in the absence of oxygen.
E) by glycolysis only.

Question 21

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

A) Krebʹs cycle
B) pentose phosphate pathway
C) glycolysis
D) Krebs cycle and glycolysis

Question 22

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

A) Two pyruvate molecules are generated.
B) One molecule of ATP is expended.
C) Two molecules of water are generated.
D) Four ATP molecules are generated via substrate-level phosphorylation.
E) Two NADH molecules are generated.

Question 23

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) 1, 2, 3
B) 1, 3, 4
C) 2, 4, 5
D) 2, 3, 5
E) All of the statements are true.

Question 24

Figure 5.8

In Figure 5.8, where is ATP produced?

A) a
B) b
C) c
D) d
E) e

Question 25

Figure 5.7 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

Question 26

Which of the following statements regarding metabolism is FALSE?

A) ATP is formed in catabolic reactions.
B) Heat may be released in both anabolic and catabolic reactions.
C) ADP is formed in anabolic reactions.
D) Anabolic reactions are degradative.

Question 27

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

A) chlorophyll.
B) H2S.
C) CO₂.
D) C6H12O6.
E) H₂O.

Question 28

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

A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph

Question 29

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) Not enough protein is provided.
B) O₂ is in the medium.
C) The temperature is too low.
D) The temperature is too high.
E) The maltose is toxic.

Question 30

Which of the following is TRUE about this reaction? NO3-+ 2H+ Pseudomonas NO₂- + H₂O Nitrate ion Nitrite ion

A) This process requires O₂.
B) This process requires the entire electron transport system.
C) This process requires light.
D) This process requires O₂ and the electron transport system.
E) This process occurs anaerobically.

Question 31

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

A) NADH and ATP are generated.
B) It involves glycolysis.
C) ATP is generated.
D) It involves the pentose phosphate pathway.
E) NADH is generated.

Question 32

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

A) noncompetitive inhibition.
B) allosteric inhibition.
C) competitive inhibition.
D) feedback inhibition.

Question 33

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

A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph

Question 34

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

A) anaerobic respirers.
B) homolactic fermenters.
C) alcohol fermenters.
D) aerobic respirers.
E) heterolactic fermenters.

Question 35

Which of the following uses glucose for carbon and energy?

A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph

Question 36

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

A) oxidizing the glucose.
B) not growing.
C) using the peptides.
D) fermenting the glucose.

Question 37

Figure 5.6 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 cannot grow anaerobically.
B) these bacteria get more energy anaerobically.
C) aerobic metabolism is more efficient than fermentation.
D) these bacteria donʹt use O₂.

Question 38

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) decrease.
B) increase.
C) stay the same.

Question 39

Cyanobacteria are a type of

A) chemoautotroph.
B) chemoheterotroph.
C) photoautotroph.
D) photoheterotroph.

Question 40

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

A) the Calvin-Benson cycle.
B) reduction.
C) fermentation.
D) photophosphorylation.
E) oxidation.

Question 41

In general, ATP is generated in catabolic pathways and expended in anabolic pathways.

Question 42

The use of enzymes is necessary to increase the activation energy requirements of a chemical reaction.

Question 43

A urease test is used to identify Mycobacterium tuberculosis because

A) M. tuberculosis produces urease.
B) some bacteria reduce nitrate ion.
C) urea accumulates during tuberculosis.
D) M. bovis can cause tuberculosis.
E) urease is a sign of tuberculosis.

Question 44

Figure 5.8

In Figure 5.8, the path labeled ʺ2ʺ is the flow of

A) energy.
B) electrons.
C) water.
D) protons.
E) glucose.

Question 45

Figure 5.8

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

A) a
B) b
C) c
D) d
E) e

Question 46

What is the most acidic place in Figure 5.8?

A) a
B) b
C) c
D) d
E) e

Question 47

Catabolic reactions are generally degradative and hydrolytic.

Question 48

Glycolysis is utilized by cells in both respiration and fermentation.

Question 49

Carbon fixation occurs during the light-independent phase of photosynthesis.

Question 50

Figure 5.8

In Figure 5.8, the structure labeled ʺ1ʺ is

A) NAD+.
B) ATP synthase.
C) cytoplasm.
D) a cell wall.
E) a plasma membrane.

Question 51

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 genetic transposable element.
C) a protease inhibitor.
D) a competitive inhibitor for reverse transcriptase.
E) a hydrolase.

Question 52

Once an enzyme has converted substrates into products, the active site reverts back to its original form.

Question 53

The pentose phosphate pathway can be characterized as an anabolic pathway.

Question 54

Both respiration and photosynthesis use water molecules for the donation of hydrogen ions.

Question 55

An apoenzyme that loses its coenzyme subunit will be non -functional.

Question 56

Both respiration and photosynthesis require the use of an electron transport chain.

Question 57

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) 2, 3, 4
B) 1, 2, 3, 4
C) 1, 2, 3
D) 1 only
E) 2, 4