Micobiology CH 5- Microbial Metabolism

Which of the following compounds is NOT an enzyme?
A) dehydrogenase
B) cellulase
C) coenzyme A
D) β-galactosidase
E) sucrase

C) coenzyme A

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

C) NAD+

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

B) photoautotroph - CO2

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 Krebs cycle is utilized.
C) It involves the reduction of an organic final electron acceptor.
D) It generates ATP.
E) It requires cytochromes.

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

What type of reaction is in Figure 5.2?
A) decarboxylation
B) transamination
C) dehydrogenation
D) oxidation
E) reduction

B) transamination

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.

E) It is converted into acetyl CoA.

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.

B) It would bind to b.

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

E) substrate-level phosphorylation

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.

A) the Krebs cycle.

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

C) c

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.

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.

From the list below, which is NOT produced during the Krebs cycle?
A) FADH2
B) NADH
C) ATP
D) NADPH
E) CO2

D) NADPH

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.

D) It requires CO2.

A bacterium that only possesses the ability to ferment obtains 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.

A) by glycolysis only.

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.

C) three ATPs.

Which biochemical process is NOT used during glycolysis?
A) substrate-level phosphorylation
B) oxidation-reduction
C) carbohydrate catabolism
D) beta oxidation
E) enzymatic reactions

D) beta oxidation

17) In noncyclic photophosphorylation, O2 is released from
A) CO2.
B) 2H2O.
C) C6H12O6.
D) sunlight.
E) chlorophyll.

B) 2H2O.

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 CO2 and H2O
D) the production of energy by oxidative-level phosphorylation
E) the production of energy by both substrate and oxidative phosphorylation

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

All of the following are required in the reactions of microbial respiration EXCEPT
A) electron transport system.
B) cytochromes.
C) a source of electrons.
D) oxygen.
E) final electron acceptor.

D) oxygen.

Increasing the temperature of a reaction will do all of the following EXCEPT
A) increase the reaction rate.
B) increase the number of molecules attaining activation energy.
C) increase the number of molecular collisions.
D) increase the activation energy.
E) increase kinetic energy of the molecules.

D) increase the activation energy.

In green and purple bacteria, electrons to reduce CO2 can come from
A) CO2.
B) H2O.
C) C6H12O6.
D) H2S.
E) chlorophyll.

D) H2S.

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 (become more alkaline).
B) decrease (become more acidic).
C) stay the same.

B) decrease (become more acidic).

Which of the following uses CO2 for carbon and H2 for energy?
A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph

A) chemoautotroph

Which of the following uses glucose for carbon and energy?
A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph

B) chemoheterotroph

Which of the following has bacteriochlorophylls and uses alcohols for carbon?
A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph

D) photoheterotroph

Cyanobacteria are a type of
A) chemoautotroph.
B) chemoheterotroph.
C) photoautotroph.
D) photoheterotroph.

C) photoautotroph

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.

A) 2, 4, 5

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.

C) heterolactic fermenters.

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.

D) Anabolic reactions are degradative.

A bacterium such as Pseudomonas uses nitrate as a final electron acceptor in an electron
transport system. All the below statements are true EXCEPT
A) the process does not yield as much ATP.
B) they can respire without O2.
C) they require light.
D) the process produces nitrite ion.
E) the process requires an electron donor.

C) they require light.

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.

E) NADH and ATP are generated.

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) Not enough protein is provided.
D) The temperature is too low.
E) The temperature is too high.

B) O2 is in the medium.

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.

C) aerobic metabolism is more efficient than fermentation.

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.

B) competitive inhibition.

If a cell is starved for ATP, which of the following pathways would most likely be shut
down?
A) Krebs cycle
B) glycolysis
C) pentose phosphate pathway
D) Krebs cycle and glycolysis

C) pentose phosphate pathway

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.

D) One molecule of ATP is expended.

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

B) b

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.

C) using the peptides.

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.

A) oxidation.

40) In Figure 5.8, where is ATP produced?
A) a
B) b
C) c
D) d
E) e

E) e

Refer to Figure 5.8. In aerobic respiration, where is water formed?
A) a
B) b
C) c
D) d
E) e

D) d

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

C) a plasma membrane.

In Figure 5.8, the path labeled "2" is the flow of
A) electrons.
B) protons.
C) energy.
D) water.
E) glucose.

B) protons.

What is the most acidic place in Figure 5.8?
A) a
B) b
C) c
D) d
E) e

A) a

45) A urease test is used to identify Mycobacterium tuberculosis because
A) urease is a sign of tuberculosis.
B) M. tuberculosis produces urease.
C) urea accumulates during tuberculosis.
D) some bacteria reduce nitrate ion.
E) M. bovis can cause tuberculosis.

B) M. tuberculosis produces urease.

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.

A) an RNA molecule capable of catalysis.

Which statements correspond to amphibolic pathways?
1. Anabolic and catabolic reactions are joined through common intermediate.
2. They are 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

B) 1, 2, 3

Why do eukaryotes generate only about 36 ATP per glucose in aerobic respiration but
prokaryotes may generate about 38 ATP?
A) eukaryotes have a less efficient electron transport system.
B) eukaryotes do not transport as much hydrogen across the mitochondrial membrane as
prokaryotes do across the cytoplasmic membrane.
C) eukaryotes must shuttle pyruvate across the mitochondrial membrane by active transport.
D) eukaryotes do not completely oxidize glucose in their respiration reactions.
E) prokaryotes possess an alternate to the Krebs cycle that generates more reduced
electron.carriers.

C) eukaryotes must shuttle pyruvate across the mitochondrial membrane by active transport.

49) In non-cyclic photophosphorylation, excited electrons ultimately
A) return to chlorophyll.
B) are used to form water.
C) combine with hydrogen ions and NADP+ to produce NADPH.
D) flow through ATP synthase.
E) generate light within the spectrum of green wavelengths.

C) combine with hydrogen ions and NADP+ to produce NADPH.

The graph shows the normal reaction rate of an enzyme and the reaction rate when a competitive
inhibitor is present. Which description below explains the appearance of the graph?
A) As the substrate concentration increases, the activity of the enzyme decreases.
B) As the substrate concentration increases, the effect of the inhibitor was overcome and enzyme activity was restored.
C) As the enzyme concentration increased, the effect of the inhibitor was overcome and enzyme activity was restored.
D) As the enzyme concentration increased, the effect of the inhibitor was more pronounced.
E) As the competitive inhibitor concentration decreased, the reaction rate also decreased.

B) As the substrate concentration increases, the effect of the inhibitor was overcome and enzyme
activity was restored.

Catabolic reactions are generally degradative and hydrolytic.

TRUE

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

FALSE

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

TRUE

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

TRUE

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

FALSE

Glycolysis is utilized by cells in both respiration and fermentation.

FALSE

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

TRUE

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

TRUE

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

FALSE

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

TRUE