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 
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. 
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

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. 
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 4

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 
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 5

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

Question 6

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 7

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

Question 8

Which of the following cannot cross the inner mitochondrial membrane?

Accepted Answer

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

Question 9

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

Accepted Answer

A) True 
 B)False

Question 10

Which enzyme catalyzes the reaction shown?

Accepted Answer

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

Question 11

Which enzyme catalyzes the reaction shown?

Accepted Answer

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

Question 12

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

Question 13

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

Question 14

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

Question 15

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. 
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 16

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

Question 17

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

Accepted Answer

A) True 
 B)False

Question 18

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

Accepted Answer

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

Question 19

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

Question 20

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

Accepted Answer

A) True 
 B)False

Exam 19: The Citric Acid Cycle

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

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

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

Fluorine is related to the citric acid cycle because:

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.

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.

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

Which of the following cannot cross the inner mitochondrial membrane?

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

Which enzyme catalyzes the reaction shown?

Which enzyme catalyzes the reaction shown?

Which of the following reactions involves substrate-level phosphorylation?

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

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

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

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

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

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

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

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

Biochemistry and the Organization of Cells

Water the Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins Enzymes

The Behavior of Proteins Enzymes Mechanisms and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids How Structure Conveys Information

Biosynthesis of Nucleic Acids Replication

Transcription of the Genetic Code the Biosynthesis of Rna

Protein Synthesis Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses Cancer and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism Cellular Signaling

Filters

The citric acid cycle is also known as the _____.