General, Organic & Biological Chemistry, 5e (Timberlake)
Chapter 23 Metabolism and Energy Production
23.1 Multiple-Choice Questions
1) When combined with electron transport, one turn of the citric acid cycle produces ________ ATP.
A) 24
B) 12
C) 10
D) 14
E) 2
2) Which coenzyme is the electron acceptor in the following reaction?
H H
| |
– C – C – → – C = C –
| | | |
A) FAD
B) NAD+
C) FMN
D) NADH
E) FADH2
3) Which coenzyme is the electron acceptor in the following reaction?
OH O
|
– C – → – C –
|
H
A) FAD
B) NAD+
C) FMN
D) NADH
E) FADH2
4) NAD+ participates in reactions that produce
A) a CH2 group.
B) a C=O bond.
C) phosphorylation.
D) ADP from ATP.
E) a C-C bond.
5) FAD is a coenzyme which usually participates in
A) oxidation of alcohols to aldehydes.
B) formation of carbon-carbon double bonds.
C) decarboxylation reactions.
D) phosphorylation reactions.
E) β-oxidation reactions.
6) In order to enter the citric acid cycle, pyruvate is first converted to
A) ate.
B) acetaldehyde.
C) citrate.
D) acetyl CoA.
E) ethanol.
7) The citric acid cycle is used in the oxidation of
A) glucose only.
B) glucose and fatty acids only.
C) fatty acids only.
D) glucose, fatty acids, and proteins.
E) proteins only.
8) What electron acceptor(s) is(are) used in the citric acid cycle?
A) FAD only
B) NAD+ only
C) NADH + FADH2 + HS – CoA
D) FMN
E) NAD+ + FAD
9) Which of the following compounds in the citric acid cycle undergoes oxidative decarboxylation?
A) citrate
B) isocitrate
C) succinate
D) fumarate
E) succinyl CoA
10) Which of the following is the net reaction for one turn of the citric acid cycle?
A) Acetyl CoA + 3 NAD+ + FAD + GDP + Pi + 2H2O → 2CO2 + 3 NADH + 3 H+ + FADH2 + HS – CoA +
GTP
B) Pyruvate + 3 NAD+ + FAD + GDP + Pi + 2H2O → 3 CO2 + 3 NADH + 3 H+ + FADH2 + GTP
C) Acetyl CoA + NAD+ + FAD + GDP + Pi → 2 CO2 + NADH + H+ + FADH2 + HS – CoA + GTP
D) Glucose + 2 NAD+ + 2GDP + 2 Pi + 2H2O → 2Pyruvate + 2 NADH + 2 H+ + GTP
E) Glucose + 2GDP + 2 Pi → 2Lactate + 2GTP
11) The citric acid cycle operates only under aerobic conditions because
A) oxygen is a reactant in the citric acid cycle.
B) oxygen is a product of the citric acid cycle.
C) CO2 is a product of the citric acid cycle.
D) the NADH and FADH2 produced by the citric acid cycle can only be reoxidized by the electron
transport chain.
E) the NAD+ and FAD produced by the citric acid cycle can only be reduced by the electron transport
chain.
12) When oxygen is in plentiful supply in the cell, pyruvate is converted to
A) CoA.
B) acetyl CoA.
C) glucose.
D) lactate.
E) fructose.
13) Which of the three major stages of metabolism includes the citric acid cycle?
A) Stage one
B) Stage two
C) Stage three
14) The citric acid cycle takes place in the
A) mitochondria.
B) cytosol.
C) cytoplasm.
D) Golgi apparatus.
E) endoplasmic reticulum.
15) Most of the energy released in the citric acid cycle is used to produce
A) glucose.
B) acetyl CoA.
C) NADH and FADH2.
D) carbon dioxide and water.
E) citric acid.
16) Another name for the citric acid cycle is
A) electron transport.
B) glycolysis.
C) the tricarboxylic acid (TCA) cycle.
D) glucolysis.
E) the transamination pathway.
17) Another name for the citric acid cycle is
A) the Krebs cycle.
B) gluconeogenesis.
C) glucose hydrolysis.
D) oxidative phosphorylation.
E) the chemiosmotic pump.
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18) In the first reaction of the citric acid cycle
A) glucose becomes pyruvate.
B) ATP is produced.
C) NADH is produced.
D) acetyl CoA reacts with oxaloacetate to give citrate.
E) pyruvate becomes CO2 and H2O.
19) During the first reaction in the citric acid cycle,
A) HS- CoA is released.
B) acetyl CoA is made.
C) a decarboxylation occurs.
D) a decomposition occurs.
E) ATP is synthesized.
20) The transformation of citrate to isocitrate in the citric acid cycle requires two ________ reactions.
A) oxidation
B) reduction
C) hydrolysis
D) decarboxylation
E) dehydration-hydration
21) The citric acid cycle step that removes the first CO2 molecule is a(n)
A) oxidative decarboxylation.
B) reduction.
C) carbonylation.
D) hydrolysis.
E) combination.
22) In the third major step of the citric acid cycle, NAD+ is converted to
A) NAS–.
B) NAD2+.
C) NADH2.
D) NAD.
E) NADH.
23) Step 5 of the citric acid cycle is the hydrolysis of succinyl CoA. In this reaction
A) the energy released is used to make GTP.
B) the energy released is used to make ATP.
C) carbon dioxide is released.
D) α-ketoglutarate is released.
E) the enzyme aconitase is needed.
24) In the hydrolysis of succinyl CoA in step 5 of the citric acid cycle, CoA is released as
A) HS-CoA.
B) HO-CoA.
C) CoA-O–.
D) CoA-S–.
E) CoA-COO–.
25) The GTP formed in step 5 of the citric acid cycle is used to make
A) carbon dioxide.
B) oxygen.
C) water.
D) CoA.
E) ATP.
26) In the dehydration of succinate to fumarate in the citric acid cycle, the coenzyme used is
A) CoA.
B) acetyl CoA.
C) NAD+.
D) NADH.
E) FAD.
27) In step 7 of the citric acid cycle, fumarate is converted to malate by a ________ reaction.
A) hydrolysis
B) dehydrogenation
C) hydrogenation
D) hydration
E) dehydration
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28) The last step in the citric acid cycle converts malate to
A) citrate.
B) isocitrate.
C) succinate.
D) fumarate.
E) oxaloacetate.
29) One method of regulation of the citric acid cycle is
A) allosteric control.
B) osmosis.
C) temperature control.
D) carbon dioxide production.
E) water concentration.
30) The process which requires oxygen to produce carbon dioxide and water is called
A) fermentation.
B) reduction.
C) decomposition.
D) oxidation.
E) respiration.
31) Which of the following metabolic pathways can occur in the absence of oxygen?
A) electron transport
B) oxidative phosphorylation
C) citric acid cycle
D) glycolysis
E) β-oxidation
32) Under anaerobic conditions, there is a net production of ________ ATP during glycolysis.
A) zero
B) two
C) four
D) six
E) eight
33) Cyanide ion and carbon monoxide inhibit
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A) cytochrome c oxidase.
B) ATP production.
C) antibiotic activity.
D) CoQ formation.
E) CoA formation.
34) In the chemiosmotic model, protons circulate through a protein complex called
A) Cyt c.
B) FMN.
C) Complex III.
D) CoQ.
E) ATP synthase.
35) The components of the electron transport chain do NOT include
A) oxygen (O2).
B) Cyt c.
C) Complex III.
D) CoQ.
E) acetyl CoA.
36) In the chemiosmotic model of oxidative phosphorylation, ATP is synthesized as
A) OH– flows through ATP synthase.
B) electrons flow through ATP synthase.
C) Ca2+ flows through ATP synthase.
D) H+ flows through ATP synthase.
E) Na+ flows through ATP synthase.
37) In electron transport, the synthesis of ATP from ADP + Pi is called
A) glycolysis.
B) fermentation.
C) oxidative phosphorylation.
D) isomerization.
E) hydrolysis.
38) In electron transport, the three protein complexes (I, III, and IV)
A) act as proton pumps, which generate a proton gradient.
B) transfer electrons from NAD+ to O2.
C) transfer electrons from FAD to O2.
D) act as electron pumps, which generate an electron gradient.
E) act as Ca2+ pumps, which generate a Ca2+ gradient.
39) In electron transport, the oxidized product from the reaction of CoQ + NADH + H+ is
A) CoQ.
B) CoQH2.
C) FADH.
D) FAD.
E) NAD+.
40) The electron carrier ________ provides 1.5 ATP via electron transport.
A) FADH2
B) NADH
C) NADPH
D) HS-CoA
E) acetyl CoA
41) Electron transport is also called
A) the citric acid cycle.
B) β-oxidation.
C) transamination.
D) the respiratory chain.
E) fermentation.
42) In electron transport, NADH and FADH2 are used to provide
A) oxygen.
B) electrons and hydrogen ions.
C) carbon atoms.
D) water and carbon dioxide.
E) thiol groups.
43) The energy released during electron transport is used to produce
A) glucose.
B) citric acid.
C) carbon dioxide.
D) ATP.
E) NADH.
44) The compounds in the respiratory chain that remove hydrogen ions and electrons from NADH are
classified as
A) oxidative transporters.
B) osmotic carriers.
C) electron carriers.
D) phosphorylators.
E) citrates.
45) One example of an electron carrier in the respiratory chain is
A) ATP.
B) GTP.
C) coenzyme Q.
D) citrate.
E) water.
46) Which is the best choice for the box labeled “Answer” in the illustration below?
A) oxidized carrier B
B) carbon dioxide
C) OH–
D) reduced carrier BH2
E) energy
47) What is the correct coefficient for ATP in the complete combustion of glucose?
C6H12O6 + 6O2 → 6CO2 + ________ ATP + 6H2O
A) 6
B) 12
C) 18
D) 24
E) 32
48) Which of the following is NOT a possible product of pyruvate under anaerobic conditions?
A) lactate
B) acetaldehyde
C) fumarate
D) ethanol
E) CO2
49) In stage three of metabolism, the overall result is to release
A) glucose and water.
B) lactate and acetyl CoA.
C) lactate and glucose.
D) glycogen and water.
E) carbon dioxide and energy.
50) Overall, one turn of the citric acid cycle produces
A) three CO2 molecules.
B) three NADH molecules.
C) two FADH2 molecules.
D) 6 ATP.
E) 2 GTP.
51) In glycolysis, glucose produces 2 pyruvate ions and a total of ________ ATP molecules.
A) 2
B) 4
C) 7
D) 8
E) 12
52) The complete oxidation of glucose produces ________ ATP molecules.
A) 2
B) 8
C) 12
D) 24
E) 32
23.2 Short Answer Questions
In this figure depicting the Stages of Metabolism taken from your text, identify the metabolic substance numbered.
1) Substance 1
2) Substance 2
3) Substance 3
4) Substance 4
5) Substance 5
6) Substance 6
7) Substance 7
8) Substance 8
9) Process 9
10) Process 10
11) Process 11
In this figure, depicting part 1 of the Citric Acid Cycle, taken from your text, identify the substances numbered.
12) Substance 12
13) Substance 13
14) Substance 14
15) Substance 15
16) Substance 16
17) Substance 17
18) Substance 18
23.3 True/False Questions
1) In reaction 4 of the citric acid cycle, α-ketoglutarase, a five-carbon keto acid, is decarboxylated.
2) In reaction 1 of the citric acid cycle, acetyl CoA reacts with oxaloacetate.
3) Citrate is one of the products of the citric acid cycle.
4) NAD+ acts as a hydrogen acceptor in metabolic reactions.
5) FADH2 is the oxidized form of FAD.
6) Cyt c is a component of complex IV.
7) The energy levels of complexes decrease as electron transport progresses.
8) 12 ATP are produced when glucose is oxidized to CO2 and H2O.
9) The conversion of ATP to ADP and inorganic phosphate produces 7.3 kcal/mole of energy.
10) The oxidation of NADH yields 2.5 ATP.
11) The oxidation of FADH2 yields 1.5 ATP.
23.4 Matching Questions
Indicate the amount of ATP produced when each of the following reactions occurs.
A) 7 ATP
B) 2 ATP
C) 32 ATP
D) 2.5 ATP
E) 10 ATP
1) complete oxidation of glucose
Objective: 23.3
Global Outcomes: GO4
2) acetyl CoA → 2CO2
Objective: 23.3
Global Outcomes: GO4
3) glucose → 2 pyruvate under aerobic conditions
Objective: 23.3
Global Outcomes: GO4
4) glucose → 2 lactate
Objective: 23.3
Global Outcomes: GO4
5) pyruvate → acetyl CoA + CO2
Objective: 23.3
Global Outcomes: GO4
Match the terms with the following descriptions.
A) oxidative phosphorylation
B) coenzyme A
6) the process that makes ATP using energy from the electron transport chain
Objective: 23.3
Global Outcomes: GO2
7) the carrier of acetyl (two-carbon) groups
Objective: 23.1
Global Outcomes: GO2
Identify each of the following metabolic pathways.
A) glycolysis
B) electron transport
C) citric acid cycle
8) the conversion of glucose to pyruvic acid
Objective: 23.1
Global Outcomes: GO2
9) the series of reactions that converts acetyl CoA to carbon dioxide and water
Objective: 23.1
Global Outcomes: GO2
10) the series of reactions that produces water
Objective: 23.2
Global Outcomes: GO2
11) the series of reactions that uses electron carriers
Objective: 23.2
Global Outcomes: GO2