Question 1

Some bacteria and anaerobic eukaryotes not using PDHpyruvate dehydrogenase)  form acetyl CoA and CO2 from pyruvate with .

Accepted Answer

A)   PDH modified with methyl groups
B)   pyruvate:ferredoxin oxidoreductase
C)   2-oxoacid dehydrogenase
D)   an isoenzyme of PDHE) A) and C)
F) B) and C)

Question 2

Malonate is a competitive inhibitor of the succinate dehydrogenase complex.

Accepted Answer

A) True 
 B)False

Question 3

The activity of dihydrolipoamide dehydrogenase E3) is inhibited by a high NADH/NAD+ ratio.

Accepted Answer

A) True 
 B)False

Question 4

Which of the following are components of the succinate dehydrogenase complex?

Accepted Answer

A)   FAD prosthetic group
B)   iron-sulfur clusters
C)   malonate
D)   All of the above
E)   A and B onlyF) C) and E)
G) A) and B)

Question 5

Pyruvate passes through the outer mitochondrial membrane by .

Accepted Answer

A)   porin proteins
B)   passive transport
C)   pyruvate translocase
D)   simple diffusion through the lipid bilayerE) None of the above
F) A) and C)

Question 6

The arrangement of subunits in the PDHpyruvate dehydrogenase)  complex ensures that .

Accepted Answer

A)   ATP is formed
B)   the product of one enzyme is delivered to the next in turn
C)   the dihydrolipoamide arm can react with NAD+
D)   acetyl CoA enters into the series of reactionsE) B) and C)
F) None of the above

Question 7

Citrate can react asymmetrically in the citric acid cycle because the enzyme aconitase

Accepted Answer

A)   binds citrate asymmetrically.
B)   binds either form of citrate.
C)   binds both forms of isocitrate.
D)   does not distinguish the -CH2COO- group.E) B) and C)
F) A) and D)

Question 8

The order of prosthetic groups as they act in the three proteins of the PDHpyruvate dehydrogenase)  complex is:

Accepted Answer

A)   FAD → thiamine pyrophosphate → NAD+
B)   FAD → thiamine pyrophosphate → dihydrolipoamide
C)   thiamine pyrophosphate → dihydrolipoamide → FAD
D)   NAD+ → FAD → dihydrolipoamideE) None of the above
F) B) and C)

Question 9

Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of carbon dioxide?

Accepted Answer

A)   fumarase
B)   α-ketoglutarate
C)   succinate
D)   isocitrateE) B) and C)
F) None of the above

Question 10

Which of the following inhibits)  pyruvate dehydrogenase kinase?

Accepted Answer

A)   pyruvate
B)   NADH
C)   acetyl-CoA
D)   All of the aboveE) A) and B)
F) A) and C)

Question 11

The enzyme pyruvate translocase is located .

Accepted Answer

A)   in the cytosol
B)   in the inner mitochondrial membrane
C)   in the mitochondrial matrix
D)   in the endoplasmic reticulumE) A) and D)
F) A) and C)

Question 12

After passing through the citric acid cycle, one mole of pyruvate will result in the formation of moles of carbon dioxide and moles)  of ATP or GTP) .

Accepted Answer

A)   2; 2
B)   2; 1
C)   3; 2
D)   3; 1E) All of the above
F) B) and D)

Question 13

The citric acid cycle oxidizes pyruvate, and some of the pathway intermediates are starting materials for many biosynthetic pathways. This means the citric acid cycle is .

Accepted Answer

A)   amplifying
B)   catabolic
C)   anabolic
D)   catabolic and anabolicE) A) and C)
F) B) and C)

Question 14

The citric acid cycle is an anaerobic pathway that occurs in the mitochondria of eukaryotes.

Accepted Answer

A) True 
 B)False

Question 15

Most of the energy released in citric acid cycle reactions is conserved in .

Accepted Answer

A)   GTP
B)   ATP
C)   NADH and QH2 
D)   ADPE) A) and C)
F) None of the above

Question 16

Which process is not implicated in the evolution of the citric acid cycle pathway?

Accepted Answer

A)   gene duplication
B)   palindromic inversion
C)   pathway extension
D)   pathway reversal
E)   enzyme theftF) A) and B)
G) A) and C)

Question 17

NAD-dependent malate dehydrogenase

Accepted Answer

A)   catalyzes the oxidation of malate to regenerate oxaloacetate.
B)   catalyzes the conversion of fumarase to malate.
C)   catalyzes a reaction which results in the formation of an NADH molecule.
D)   All of the above
E)   A and C onlyF) B) and E)
G) A) and E)

Question 18

Which enzyme is the same in both the pyruvate dehydrogenase and α-ketoglutarate complexes?

Accepted Answer

A)   dihydrolipoamide dehydrogenase
B)   aconitase
C)   pyruvate decarboxylase
D)   The two complexes have no components that are similar.E) A) and C)
F) A) and D)

Question 19

Carbons from acetyl CoA are transferred to the citric acid cycle. Which is the first round of the citric acid cycle that could possibly release a carbon atom originating from this acetyl CoA?

Accepted Answer

A)   first round
B)   second round
C)   third round
D)   fourth roundE) B) and C)
F) C) and D)

Question 20

About how many total ATP equivalents are generated by the complete oxidation of one molecule of acetyl CoA?

Accepted Answer

A)   1.5
B)   2.5
C)   3
D)   10
E)   30F) B) and E)
G) B) and D)

Exam 13: The Citric Acid Cycle

Which of the following inhibits) pyruvate dehydrogenase kinase?

Correct AnswerverifiedShow Answer

Pyruvate passes through the outer mitochondrial membrane by .

Correct AnswerverifiedShow Answer

Most of the energy released in citric acid cycle reactions is conserved in .

Correct AnswerverifiedShow Answer

The activity of dihydrolipoamide dehydrogenase E3) is inhibited by a high NADH/NAD+ ratio.

Correct AnswerverifiedShow Answer

Citrate can react asymmetrically in the citric acid cycle because the enzyme aconitase

Correct AnswerverifiedShow Answer

Which process is not implicated in the evolution of the citric acid cycle pathway?

Correct AnswerverifiedShow Answer

Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of carbon dioxide?

Correct AnswerverifiedShow Answer

Malonate is a competitive inhibitor of the succinate dehydrogenase complex.

Correct AnswerverifiedShow Answer

The citric acid cycle oxidizes pyruvate, and some of the pathway intermediates are starting materials for many biosynthetic pathways. This means the citric acid cycle is .

Correct AnswerverifiedShow Answer

About how many total ATP equivalents are generated by the complete oxidation of one molecule of acetyl CoA?

Correct AnswerverifiedShow Answer

The order of prosthetic groups as they act in the three proteins of the PDHpyruvate dehydrogenase) complex is:

Correct AnswerverifiedShow Answer

The arrangement of subunits in the PDHpyruvate dehydrogenase) complex ensures that .

Correct AnswerverifiedShow Answer

The citric acid cycle is an anaerobic pathway that occurs in the mitochondria of eukaryotes.

Correct AnswerverifiedShow Answer

NAD-dependent malate dehydrogenase

Correct AnswerverifiedShow Answer

Which of the following are components of the succinate dehydrogenase complex?

Correct AnswerverifiedShow Answer

After passing through the citric acid cycle, one mole of pyruvate will result in the formation of moles of carbon dioxide and moles) of ATP or GTP) .

Correct AnswerverifiedShow Answer

Which enzyme is the same in both the pyruvate dehydrogenase and α-ketoglutarate complexes?

Correct AnswerverifiedShow Answer

Carbons from acetyl CoA are transferred to the citric acid cycle. Which is the first round of the citric acid cycle that could possibly release a carbon atom originating from this acetyl CoA?

Correct AnswerverifiedShow Answer

The enzyme pyruvate translocase is located .

Correct AnswerverifiedShow Answer

Some bacteria and anaerobic eukaryotes not using PDHpyruvate dehydrogenase) form acetyl CoA and CO2 from pyruvate with .

Correct AnswerverifiedShow Answer

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The activity of dihydrolipoamide dehydrogenase E₃) is inhibited by a high NADH/NAD⁺ ratio.

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Some bacteria and anaerobic eukaryotes not using PDHpyruvate dehydrogenase) form acetyl CoA and CO₂from pyruvate with .

Correct Answer
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