CHAPTER 23: BIOCHEMICAL ENERGY PRODUCTION
MULTIPLE CHOICE
1. Which of the following statements about metabolism is correct? Ans. A
a. Metabolism is the sum total of all the biochemical reactions that take place in a
living organism.
b. Anabolic reaction sequences usually produce energy.
c. A metabolic pathway may only be cyclic in which a series of reaction regenerates
the first reactant.
d. The process of polysaccharide digestion is an anabolic process.
2. Which of the following statements about mitochondria is correct? Ans. D
a. The outer membrane of mitochondria is not permeable to any molecules.
b. The interior region of a mitochondrion is the intermembrane space.
c. The folds of the outer membrane are called cristae.
d. Mitochondria are located within the cellular cytosol.
3. Which of the following diagrams gives the correct identities and arrangement of the structural
subunits in coenzyme A? Ans. C
4. The missing structural subunit in the following diagram for flavin adenine dinucleotide is:
Ans. C
a.
b.
c.
d.
phosphate
ribose
ribitol
deoxyribose
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5. The correct notation for the reduced form of nicotinamide adenine dinucleotide is: Ans. A
a. NAD+
b. NAD
c. NADH
d. NADH2
6. Which of the following is a correct skeletal equation for a hydrolysis reaction involving
adenosine phosphates? Ans. C
a. ATP → ADP + 2Pi
b. ADP → AMP + 2Pi
c. ATP → AMP + PPi
d. ATP → ADP + PPi
7. The “fuel” for the citric acid cycle is: Ans. A
a. acetyl CoA
b. citric acid
c. citrate ion
d. oxaloacetate ion
9. Which of the following is a correct general description of the reaction that occurs in the first
step of the citric acid cycle? Ans. A
a. C2 + C4 → C6
b. C3 + C3 → C6
c. C2 + C2 + C2 → C6
d. C4 + C4 → C6 + C2
10. How many NADH and FADH2 molecules are produced, respectively, during one turn of the
citric acid cycle? Ans. B
a. two, two
b. three, one
c. one, three
d. two, three
11. In which of the following listings of citric acid cycle intermediates are the compounds listed
in the order in which they are encountered in a turn of the cycle? Ans. B
a. citrate, oxaloacetate, fumarate
b. isocitrate, succinyl CoA, oxaloacetate
c. fumarate, malate, alpha-ketoglutarate
d. oxaloacetate, succinate, citrate
12. At which step in the electron transport chain does O2 participate? Ans. D
a. first step
b. second step
c. next to last step
d. last step
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13. Which of the following sets of electron carriers is associated with the electron transport chain
reactions that occur at protein complex I? Ans. B
a. CoQ
b. NADH
c. cyt c
d. FADH2
14. ATP synthesis via oxidative phosphorylation depends on the passage of which of the
following species through membrane-bound ATP synthase? Ans. C
a. NADH
b. FADH2
c. H+
d. NAD+
15. How many moles of ATP result from the entry of 2 moles of FADH2 into the electron
transport chain? Ans. B, each one produces 1.5
a. 2
b. 3
c. 4
d. 5
16. How many ATP molecules result from the "processing" of 10 acetyl CoA molecule through
the common metabolic pathway? Ans. C , each acetyl-CoA produces 10 ATPs
a. 20
b. 80
c. 100
d. 240
17. In a mitochondrion: Ans. A
a. The inner membrane separates the matrix from the intermembrane space.
b. The inner membrane is more permeable than the outer membrane.
c. ATP-synthase complexes are found on the folds of the outer membrane.
d. More than one correct response.
e. No correct response.
18. Which of the following substances does not contain a B vitamin as a structural subunit? Ans.
E, all three contain B vitamins
a. flavin adenine dinucleotide
b. nicotinamide adenine dinucleotide
c. coenzyme A
d. more than one correct response
e. no correct response
19. Which of the following substances contains two or more high energy phosphate bonds? Ans.
A
a.
b.
c.
d.
ATP
ADP
AMP
more than one correct response
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e. no correct response
20. Which of the following is a correct letter designation for the reduced form of a coenzyme?
Ans. B
a. NAD+
b. FADH2
c. NADH2
d. more than one correct response
e. no correct response
21. Which of the following are products of the citric acid cycle? Ans. E
a. acetyl CoA and NAD+
b. acetyl CoA and CO2
c. CO2 and H2O
d. more than one correct response
e. no correct response
22. Which of the following citric acid cycle intermediates is decarboxylated (produces CO2)
during the operation of the cycle? Ans. E
oxaloacetate
isocitrate
succinate
more than one correct response
no correct response
a.
b.
c.
d.
e.
23. In which of the following citric acid cycle reactions does the coenzyme FAD participate? Ans.
B
a.
b.
c.
d.
e.
citrate → isocitrate
succinate → fumarate
malate → oxaloacetate
more than one correct response
no correct response
24. Which of the following carry electrons from the citric acid cycle to the electron carriers of the
electron transport chain? Ans. C
a. CoA
b. NAD+
c. FADH2
d. more than one correct response
e. no correct response
25. At which protein complex site in the electron transport chain does proton pumping occur?
Ans. D, both A and C
a. protein complex I
b. protein complex II
c. protein complex III
d. more than one correct response
e. no correct response
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Use the following to answer the questions below:
In each of the following multiple-choice questions characterize EACH of the three given
statements as being TRUE or FALSE and then indicate the collective true-false status of the
statements using the choices:
a) All three statements are true.
b) Two of the three statements are true.
c) Only one of the statements is true.
d) None of the statements is true.
26. Statements: Ans. B, 1 and 3 are correct for us
(1) In the last step of the ETC, molecular oxygen is converted to water.
(2) The B vitamin portion of the structure of coenzyme A, which involves riboflavin, is the
reactive site in the molecule.
(3) All of the reactions of the CAC take place in the mitochondrial matrix.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
28. Statements: Ans. D
(1) FADH2 is the oxidized form of the coenzyme flavin adenine dinucleotide.
(2) All of the electron carriers of the ETC contain iron, and one of them also contains copper.
(3) One turn of the CAC generates two CO2 molecules, two NADH molecules, and two FAD2
molecules.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
29. Statements: Ans. B, 1 and 2 are correct for us
(1) Both ribosomes and mitochondria are examples of organelles.
(2) Cytochromes are heme-containing proteins that can undergo reversible oxidation and
reduction.
(3) The electrons that pass through the various steps of the ETC lose some energy with each
transfer along the chain.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
30. Statements: Ans. B, 1 and 3 are correct
(1) In the first step of the CAC, a C2 molecule and a C4 molecule combine to produce a C6
molecule.
(2) ATP, ADP, and AMP differ from each other in the number of adenine subunits present.
(3) The process by which ATP is produced during the operation of the ETC is called
oxidative phosphorylation.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
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d. None of the statements is true.
31. Statements: Ans. A
(1) High-energy phosphate compounds contain one or more strained bonds that release
above-average amounts of energy when broken.
(2) In the ETC, NADH is oxidized to NAD+.
(3) The “fuel” for the CAC is acetyl CoA.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
32. Statements: Ans. A
(1) Some, but not all, protein complex sites associated with the ETC serve as proton pumps.
(2) The rate at which the CAC operates is controlled by the body's need for ATP.
(3) Anabolic reactions usually require energy input in order to proceed.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
NUMERIC RESPONSE
Use the following to answer the questions below:
For each of the molecular structural characteristics, select the correct molecule from the
response list. Responses may be used more than once or need not be used at all.
a) ATP
b) CoA
c) FAD
d) NAD+
33. Contains a pantothenic acid subunit; Ans. B
34. Contains a phosphorylated ribose subunit; Ans. B
35. Does not contain a B vitamin as part of its structure; Ans. A
36. Reactive site in the molecule is a –SH group; Ans. B
37. Contains a ribitol subunit; Ans. C
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