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
Answer: C
Objective: 23.1
Global Outcomes: GO2
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
Answer: A
Objective: 23.1
Global Outcomes: GO2
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
Answer: B
Objective: 23.1
Global Outcomes: GO2
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.
Answer: B
Objective: 23.1
Global Outcomes: GO2
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.
Answer: B
Objective: 23.1
Global Outcomes: GO2
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.
Answer: D
Objective: 23.1
Global Outcomes: GO2
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.
Answer: D
Objective: 23.1
Global Outcomes: GO2
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
Answer: E
Objective: 23.1
Global Outcomes: GO2
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
Answer: B
Objective: 23.1
Global Outcomes: GO2
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
Answer: A
Objective: 23.1
Global Outcomes: GO2
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.
Answer: D
Objective: 23.1
Global Outcomes: GO2
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.
Answer: B
Objective: 23.1
Global Outcomes: GO2
13) Which of the three major stages of metabolism includes the citric acid cycle?
A) Stage one
B) Stage two
C) Stage three
Answer: C
Objective: 23.1
Global Outcomes: GO2
14) The citric acid cycle takes place in the
A) mitochondria.
B) cytosol.
C) cytoplasm.
D) Golgi apparatus.
E) endoplasmic reticulum.
Answer: A
Objective: 23.1
Global Outcomes: GO7
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.
Answer: C
Objective: 23.1
Global Outcomes: GO2
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.
Answer: C
Objective: 23.1
Global Outcomes: GO7
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.
Answer: A
Objective: 23.1
Global Outcomes: GO7
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.
Answer: D
Objective: 23.1
Global Outcomes: GO2
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.
Answer: A
Objective: 23.1
Global Outcomes: GO2
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
Answer: E
Objective: 23.1
Global Outcomes: GO2
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.
Answer: A
Objective: 23.1
Global Outcomes: GO2
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.
Answer: E
Objective: 23.1
Global Outcomes: GO2
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.
Answer: A
Objective: 23.1
Global Outcomes: GO2
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-.
Answer: A
Objective: 23.1
Global Outcomes: GO2
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.
Answer: E
Objective: 23.1
Global Outcomes: GO2
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.
Answer: E
Objective: 23.1
Global Outcomes: GO2
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
Answer: D
Objective: 23.1
Global Outcomes: GO2
28) The last step in the citric acid cycle converts malate to
A) citrate.
B) isocitrate.
C) succinate.
D) fumarate.
E) oxaloacetate.
Answer: E
Objective: 23.1
Global Outcomes: GO2
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.
Answer: A
Objective: 23.1
Global Outcomes: GO2
30) The process which requires oxygen to produce carbon dioxide and water is called
A) fermentation.
B) reduction.
C) decomposition.
D) oxidation.
E) respiration.
Answer: E
Objective: 23.2
Global Outcomes: GO2
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
Answer: D
Objective: 23.2
Global Outcomes: GO2
32) Under anaerobic conditions, there is a net production of ______ATP during glycolysis.
A) zero
B) two
C) four
D) six
E) eight
Answer: B
Objective: 23.2
Global Outcomes: GO4
33) Cyanide ion and carbon monoxide inhibit
A) cytochrome c oxidase.
B) ATP production.
C) antibiotic activity.
D) CoQ formation.
E) CoA formation.
Answer: A
Objective: 23.2
Global Outcomes: GO2
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.
Answer: E
Objective: 23.2
Global Outcomes: GO2
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.
Answer: E
Objective: 23.2
Global Outcomes: GO2
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.
Answer: D
Objective: 23.2
Global Outcomes: GO2
37) In electron transport, the synthesis of ATP from ADP + Pi is called
A) glycolysis.
B) fermentation.
C) oxidative phosphorylation.
D) isomerization.
E) hydrolysis.
Answer: C
Objective: 23.2
Global Outcomes: GO2
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.
Answer: A
Objective: 23.2
Global Outcomes: GO2
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+.
Answer: E
Objective: 23.2
Global Outcomes: GO2
40) The electron carrier ______provides 1.5 ATP via electron transport.
A) FADH2
B) NADH
C) NADPH
D) HS-CoA
E) acetyl CoA
Answer: A
Objective: 23.2
Global Outcomes: GO2
41) Electron transport is also called
A) the citric acid cycle.
B) β-oxidation.
C) transamination.
D) the respiratory chain.
E) fermentation.
Answer: D
Objective: 23.2
Global Outcomes: GO2
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.
Answer: B
Objective: 23.2
Global Outcomes: GO2
43) The energy released during electron transport is used to produce
A) glucose.
B) citric acid.
C) carbon dioxide.
D) ATP.
E) NADH.
Answer: D
Objective: 23.2
Global Outcomes: GO2
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.
Answer: C
Objective: 23.2
Global Outcomes: GO2
45) One example of an electron carrier in the respiratory chain is
A) ATP.
B) GTP.
C) coenzyme Q.
D) citrate.
E) water.
Answer: C
Objective: 23.2
Global Outcomes: GO2
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
Answer: D
Objective: 23.2
Global Outcomes: GO2
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
Answer: E
Objective: 23.3
Global Outcomes: GO4
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
Answer: C
Objective: 23.3
Global Outcomes: GO2
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.
Answer: E
Objective: 23.3
Global Outcomes: GO2
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.
Answer: B
Objective: 23.3
Global Outcomes: GO2
51) In glycolysis, glucose produces 2 pyruvate ions and a total of ______ATP molecules.
A) 2
B) 4
C) 7
D) 8
E) 12
Answer: C
Objective: 23.3
Global Outcomes: GO4
52) The complete oxidation of glucose produces ______ATP molecules.
A) 2
B) 8
C) 12
D) 24
E) 32
Answer: E
Objective: 23.3
Global Outcomes: GO4
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
Answer: proteins
Objective: 23.1
Global Outcomes: GO2
2) Substance 2
Answer: carbohydrates or polysaccharides
Objective: 23.1
Global Outcomes: GO2
3) Substance 3
Answer: lipids
Objective: 23.1
Global Outcomes: GO2
4) Substance 4
Answer: pyruvate
Objective: 23.1
Global Outcomes: GO2
5) Substance 5
Answer: acetyl CoA
Objective: 23.1
Global Outcomes: GO2
6) Substance 6
Answer: carbon dioxide
Objective: 23.1
Global Outcomes: GO2
7) Substance 7
Answer: ATP
Objective: 23.1
Global Outcomes: GO2
8) Substance 8
Answer: oxygen
Objective: 23.1
Global Outcomes: GO2
9) Process 9
Answer: citric acid cycle or Krebs cycle or tricarboxylic acid cycle
Objective: 23.1
Global Outcomes: GO2
10) Process 10
Answer: electron transport
Objective: 23.1
Global Outcomes: GO2
11) Process 11
Answer: oxidative phosphorylation
Objective: 23.1
Global Outcomes: GO2
In this figure, depicting part 1 of the Citric Acid Cycle, taken from your text, identify the substances numbered.
12) Substance 12
Answer: acetyl CoA
Objective: 23.1
Global Outcomes: GO2
13) Substance 13
Answer: citrate
Objective: 23.1
Global Outcomes: GO2
14) Substance 14
Answer: carbon dioxide