Microbiology: An Introduction, 13e (Tortora et al.)
Chapter 5 Microbial Metabolism
5.1 Multiple-Choice Questions
1) Which of the following compounds is NOT an enzyme?
A) dehydrogenase
B) cellulase
C) coenzyme A
D) β-galactosidase
E) sucrase
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
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
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 Krebs cycle is utilized.
C) It involves the reduction of an organic final electron acceptor.
D) It generates ATP.
E) It requires cytochromes.
5) Figure 5.2
What type of reaction is in Figure 5.2?
A) decarboxylation
B) transamination
C) dehydrogenation
D) oxidation
E) reduction
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.
7) 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.
8) Figure 5.4
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
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.
10) 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
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.
12) From the list below, which is NOT produced during the Krebs cycle?
A) FADH2
B) NADH
C) ATP
D) NADPH
E) CO2
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.
14) 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.
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.
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
17) In noncyclic photophosphorylation, O2 is released from
A) CO2.
B) 2H2O.
C) C6H12O6.
D) sunlight.
E) chlorophyll.
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 CO2 and H2O
D) the production of energy by oxidative-level phosphorylation
E) the production of energy by both substrate and oxidative phosphorylation
19) 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.
20) 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.
21) In green and purple bacteria, electrons to reduce CO2 can come from
A) CO2.
B) H2O.
C) C6H12O6.
D) H2S.
E) chlorophyll.
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 (become more alkaline).
B) decrease (become more acidic).
C) stay the same.
23) Which of the following uses CO2 for carbon and H2 for energy?
A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph
24) Which of the following uses glucose for carbon and energy?
A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph
25) Which of the following has bacteriochlorophylls and uses alcohols for carbon?
A) chemoautotroph
B) chemoheterotroph
C) photoautotroph
D) photoheterotroph
26) Cyanobacteria are a type of
A) chemoautotroph.
B) chemoheterotroph.
C) photoautotroph.
D) photoheterotroph.
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.
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.
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.
30) 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.
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.
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) O2 is in the medium.
C) Not enough protein is provided.
D) The temperature is too low.
E) The temperature is too high.