Question 1

Which group of small molecules best fit the boxes associated with the reaction shown?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV

Question 2

The conversion of malate to oxaloacetate has a high + Δ G (it is endergonic) . It can take place because:

Accepted Answer

A)   It is coupled to hydrolysis of the GTP produce earlier in the cycle.
B)   It is coupled to hydrolysis of ATP from other sources.
C)   It involves a substrate level phosphorylation.
D)   The oxaloacetate product is used up in the subsequent reaction.
E)   It is coupled to a strong reduction reaction.

Question 3

One round of the citric acid cycle generates about ten equivalents of ATP.

Accepted Answer

A) True 
 B)False

Question 4

Exhibit 19A The following compounds are all intermediates in the citric acid cycle.  Refer to Exhibit 19A. Which intermediate is formed from acetyl-CoA and oxaloacetate.

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5

Question 5

The enzyme "aconitase" is also known as "condensing enzyme"

Accepted Answer

A) True 
 B)False

Question 6

Which enzyme catalyzes the reaction shown?

Accepted Answer

A)   isocitrate dehydrogenase
B)   malate dehydrogenase
C)   fumarase
D)   succinate dehydrogenase
E)   none of these

Question 7

The "energy charge" in a cell is important in the control of metabolism.

Accepted Answer

A) True 
 B)False

Question 8

​ The citric acid cycle is also known as the _____.

Accepted Answer

A)   Calvin cycle
B)   Krebs cycle
C)   Embden-Meyerhof cycle
D)   Kolb's cycle

Question 9

Which of the following reactions involves substrate-level phosphorylation?

Accepted Answer

A)   isocitrate → α -ketoglutarate
B)   citrate → isocitrate
C)   succinate → fumarate
D)   succinyl-CoA → succinate
E)   acetyl-CoA + oxaloacetate → citrate

Question 10

Which of the following statements concerning the glyoxylate pathway is false ?

Accepted Answer

A)   It utilizes one mole of acetyl-CoA per cycle.
B)   It can produce a net synthesis of 4-carbon fragments that are intermediates of the citric acid cycle.
C)   It usually occurs in the mitochondria
D)   It is the main pathway that allows for synthesis of sugars from acetyl-CoA.

Question 11

Which of the following statements concerning the citric acid cycle as the central metabolic pathway is true ?

Accepted Answer

A)   It is involved in the metabolism of sugars and amino acids.
B)   It is involved in the metabolism of amino acids and lipids.
C)   It links anaerobic metabolism to aerobic metabolism.
D)   Many of its intermediates are starting points for synthesis of a variety of compounds.
E)   All of these are reasons why the citric acid cycle is considered to be the central pathway.

Question 12

The reaction of the citric acid cycle that does not take place in the mitochondrial matrix is the one catalyzed by:

Accepted Answer

A)   fumarase
B)   citrate synthase
C)   isocitrate dehydrogenase
D)   succinate dehydrogenase
E)   All of these reactions take place in the matrix

Question 13

Which of the following is not a component of the pyruvate dehydrogenase complex?

Accepted Answer

A)   pyruvate dehydrogenase
B)   dihydrolipoyl transacetylase
C)   dihydrolipoyl dehydrogenase
D)   pyruvate dehydrogenase kinase
E)   aconitase

Question 14

Which group of small molecules best fit the boxes associated with the reaction shown?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV

Question 15

Most of the products of the catabolism of sugars, fats and amino acids enter the citric acid cycle as:

Accepted Answer

A)   pyruvate
B)   acetyl-CoA
C)   malate
D)   all of these
E)   none of these

Question 16

Which of the following cannot cross the inner mitochondrial membrane?

Accepted Answer

A)   malate
B)   phosphoenolpyruvate
C)   succinyl-CoA
D)   oxaloacetate

Question 17

Isocitrate has _____ possible isomers, out of which only one is produced in the isomerization of citrate to isocitrate.

Accepted Answer

A)   three
B)   two
C)   four
D)   six

Question 18

Weight loss in humans can be difficult to achieve, since we lack the ability to convert our fats to sugars, and it is difficult to change our metabolism to using fats as a primary energy source.

Accepted Answer

A) True 
 B)False

Question 19

Fluorine is related to the citric acid cycle because:

Accepted Answer

A)   fluoroacetyl-CoA is also a substrate for citrate synthase
B)   fluoroacetate, found in poisonous plants, acts as an inhibitor of aconitase
C)   fluorocitrate acts as a potent inhibitor of the citric acid cycle
D)   all of these

Question 20

Which enzyme catalyzes the reaction shown?

Accepted Answer

A)   isocitrate dehydrogenase
B)   pyruvate dehydrogenase
C)   fumarase
D)   succinate dehydrogenase
E)   none of these

Exam 19: The Citric Acid Cycle

Which group of small molecules best fit the boxes associated with the reaction shown?

Correct AnswerverifiedShow Answer

Fluorine is related to the citric acid cycle because:

Correct AnswerverifiedShow Answer

The reaction of the citric acid cycle that does not take place in the mitochondrial matrix is the one catalyzed by:

Correct AnswerverifiedShow Answer

​ The citric acid cycle is also known as the _____.

Correct AnswerverifiedShow Answer

The enzyme "aconitase" is also known as "condensing enzyme"

Correct AnswerverifiedShow Answer

Which of the following cannot cross the inner mitochondrial membrane?

Correct AnswerverifiedShow Answer

Which enzyme catalyzes the reaction shown?

Correct AnswerverifiedShow Answer

Most of the products of the catabolism of sugars, fats and amino acids enter the citric acid cycle as:

Correct AnswerverifiedShow Answer

Which enzyme catalyzes the reaction shown?

Correct AnswerverifiedShow Answer

Which of the following statements concerning the glyoxylate pathway is false ?

Correct AnswerverifiedShow Answer

The "energy charge" in a cell is important in the control of metabolism.

Correct AnswerverifiedShow Answer

Which of the following is not a component of the pyruvate dehydrogenase complex?

Correct AnswerverifiedShow Answer

The conversion of malate to oxaloacetate has a high + Δ G (it is endergonic) . It can take place because:

Correct AnswerverifiedShow Answer

Which of the following statements concerning the citric acid cycle as the central metabolic pathway is true ?

Correct AnswerverifiedShow Answer

Which group of small molecules best fit the boxes associated with the reaction shown?

Correct AnswerverifiedShow Answer

Exhibit 19A The following compounds are all intermediates in the citric acid cycle. Refer to Exhibit 19A. Which intermediate is formed from acetyl-CoA and oxaloacetate.

Correct AnswerverifiedShow Answer

Isocitrate has _____ possible isomers, out of which only one is produced in the isomerization of citrate to isocitrate.

Correct AnswerverifiedShow Answer

One round of the citric acid cycle generates about ten equivalents of ATP.

Correct AnswerverifiedShow Answer

Which of the following reactions involves substrate-level phosphorylation?

Correct AnswerverifiedShow Answer

Weight loss in humans can be difficult to achieve, since we lack the ability to convert our fats to sugars, and it is difficult to change our metabolism to using fats as a primary energy source.

Correct AnswerverifiedShow Answer

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The citric acid cycle is also known as the _____.

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