Deck 5: Microbial Metabolism

Question 1

Which of the following compounds is NOT an enzyme?

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

Answer 1

A

Question 2

Fatty acids are oxidized in

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

Answer 2

D

Question 3

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

A) glycolysis
B) Kreb's cycle
C) pentose phosphate pathway
D) Krebs cycle and glycolysis

Answer 3

C

Question 4

Which of the following is the best definition of fermentation?

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

Question 5

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) The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.
D) No final electron acceptor is required.
E) It occurs in the Krebs cycle.

Question 6

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 O₂.
C) Electrons are passed through a series of carriers to an organic compound.
D) ATP is directly transferred from a substrate to ADP.

Question 7

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

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

Question 8

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 9

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

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

Question 10

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

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

Question 11

Which of the following is NOT necessary for respiration?

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

Question 12

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 don't use O₂.
B) these bacteria cannot grow anaerobically.
C) aerobic metabolism is more efficient than fermentation.
D) these bacteria get more energy anaerobically.

Question 13

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

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

Question 14

Which of the following statements about photophosphorylation is FALSE?

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

Question 15

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

Question 16

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) oxidation.
E) photophosphorylation.

Question 17

Which organism is NOT correctly matched to its energy source?

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

Question 18

A urease test is used to identify Myobacterium tuberculosis because

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

Question 19

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

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

Question 20

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

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

Question 21

A strictly fermentative bacterium produces energy

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

Question 22

Figure 5.8

In Figure 5.8, the structure labeled "1" is

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

Question 23

Figure 5.8

What is the most acidic place in Figure 5.8?

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

Question 24

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

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

Question 25

Which of the following is TRUE about this reaction?

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

Question 26

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

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

Question 27

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

Question 28

Which of the following statements regarding metabolism is FALSE?

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

Question 29

Figure 5.8

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

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

Question 30

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 31

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

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

Question 32

Which of the following statements about beta oxidation is FALSE?

A) It is a method of catabolizing fatty acids.
B) It is a step in glycolysis.
C) It is used in petroleum degradation.
D) It involves the formation of acetyl- CoA.
E) It involves the formation of 2- carbon units.

Question 33

Figure 5.2

What type of reaction is in Figure 5.2?

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

Question 34

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 35

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

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

Question 36

In noncyclic photophosphorylation, O₂ is released from

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

Question 37

Which of the following uses glucose for carbon and energy?

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

Question 38

Figure 5.1

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

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

Question 39

Cyanobacteria are a type of

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

Question 40

Figure 5.4

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

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

Question 41

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

Question 42

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

Question 43

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

Question 44

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 45

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

Question 46

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

Question 47

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

Question 48

Which of the following statements about anaerobic respiration is FALSE?

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

Question 49

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

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

Question 50

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

Question 51

You look in the refrigerator and find some orange drink you had forgotten was there. The drink now has an "off" taste and bubbles. What is the most likely explanation for the changes in the drink?

Question 52

Glycolysis is utilized by cells in both respiration and fermentation.

Question 53

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

Question 54

Figure 5.8

In Figure 5.8, where is ATP produced?

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

Question 55

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

Question 56

Catabolic reactions are generally degradative and hydrolytic.

Question 57

Streptococcus lacks an electron transport chain. How does this bacterium reoxidize NADH? Where is the NADH formed?