Question 1

The reactions in which succinate is converted to oxaloacetate are,in order

Accepted Answer

A)  an oxidation, a dehydration, and an oxidation 
B)  three successive oxidation reactions 
C)  an oxidative decarboxylation, a dehydration, and a condensation 
D)  a condensation, a dehydration, and an oxidative decarboxylation 
A)  an oxidation, a dehydration, and an oxidation 
B)  three successive oxidation reactions 
C)  an oxidative decarboxylation, a dehydration, and a condensation 
D)  a condensation, a dehydration, and an oxidative decarboxylation

Question 2

Exhibit 19A   The following compounds are all intermediates in the citric acid cycle.
Refer to Exhibit 19A.Which intermediate becomes bonded to Coenzyme A during the cycle?

Accepted Answer

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

Question 3

Which of the following describes a use for acetyl-CoA as an important intermediate in metabolism?

Accepted Answer

A)  Breakdown to CO2 and water, yielding much energy. 
B)  Synthesis of terpenes and steroids. 
C)  Synthesis of oxaloacetate in plants. 
D)  Synthesis of fatty acids. 
E)  All of these are reasons why acetyl-CoA is a central molecule in metabolism. 
A)  Breakdown to CO2 and water, yielding much energy. 
B)  Synthesis of terpenes and steroids. 
C)  Synthesis of oxaloacetate in plants. 
D)  Synthesis of fatty acids. 
E)  All of these are reasons why acetyl-CoA is a central molecule in metabolism.

Question 4

Which of these enzymes is most similar to pyruvate dehydrogenase?

Accepted Answer

A)  Alpha-Ketoglutarate Dehydrogenase complex. 
B)  IsoCitrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  None of these enzymes is similar to pyruvate dehydrogenase. 
A)  Alpha-Ketoglutarate Dehydrogenase complex. 
B)  IsoCitrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  None of these enzymes is similar to pyruvate dehydrogenase.

Question 5

In the conversion of succinyl-CoA to succinate,GTP is produced from GDP in a reaction in which the source of the added phosphate is

Accepted Answer

A)  ATP. 
B)  ADP. 
C)  phosphenolpyruvate. 
D)  inorganic phosphate ion. 
A)  ATP. 
B)  ADP. 
C)  phosphenolpyruvate. 
D)  inorganic phosphate ion.

Question 6

The citric acid cycle is the only metabolic pathway that can be used both as an anabolic and as a catabolic pathway.

Accepted Answer

A) True 
 B)False

Question 7

Which of the following vitamins and enzyme cofactors are used by the pyruvate dehydrogenase complex during oxidative decarboxylation?

Accepted Answer

A)  Lipoic Acid. 
B)  Niacin. 
C)  Pantothenic Acid. 
D)  Thiamine. 
E)  All of these 
A)  Lipoic Acid. 
B)  Niacin. 
C)  Pantothenic Acid. 
D)  Thiamine. 
E)  All of these

Question 8

The only difference between succinate and fumarate is the geometry around their double bonds,one contains a cis double bond and the other contains a trans double bond.

Accepted Answer

A) True 
 B)False

Question 9

Which of the following enzymes is not a control point of the citric acid cycle?

Accepted Answer

A)  citrate synthase 
B)  isocitrate dehydrogenase 
C)  aconitase 
D)  the a-ketoglutarate dehydrogenase complex 
A)  citrate synthase 
B)  isocitrate dehydrogenase 
C)  aconitase 
D)  the a-ketoglutarate dehydrogenase complex

Question 10

Which of the following is true regarding the control of pyruvate dehydrogenase?

Accepted Answer

A)  It is inhibited by ATP 
B)  It is inhibited by NAD+ 
C)  It is activated by acetyl-CoA 
D)  It is inhibited by succinyl-CoA 
E)  none of these are true 
A)  It is inhibited by ATP 
B)  It is inhibited by NAD+ 
C)  It is activated by acetyl-CoA 
D)  It is inhibited by succinyl-CoA 
E)  none of these are true

Question 11

The production of malate in the glyoxylate pathway is important,since it can be readily converted to phosphoenolpyruvate and then to sugars.

Accepted Answer

A) True 
 B)False

Question 12

Thiamine pyrophosphate carries a ____ carbon unit.

Accepted Answer

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

Question 13

Which of the following enzymes does not use NAD+ for oxidation?

Accepted Answer

A)  Alpha-Ketoglutarate Dehydrogenase complex. 
B)  IsoCitrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  All of these enzymes use NAD+ 
A)  Alpha-Ketoglutarate Dehydrogenase complex. 
B)  IsoCitrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  All of these enzymes use NAD+

Question 14

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 15

Which enzyme catalyzes the reaction shown?

Accepted Answer

A)  isocitrate dehydrogenase 
B)  malate dehydrogenase 
C)  fumarase 
D)  succinate dehydrogenase 
A)  isocitrate dehydrogenase 
B)  malate dehydrogenase 
C)  fumarase 
D)  succinate dehydrogenase

Question 16

Which of the following enzymes is allosterically activated by NAD+?

Accepted Answer

A)  isocitrate dehydrogenase 
B)  succinyl-CoA synthetase 
C)  succinate dehydrogenase 
D)  fumarase 
A)  isocitrate dehydrogenase 
B)  succinyl-CoA synthetase 
C)  succinate dehydrogenase 
D)  fumarase

Question 17

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 18

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 does not occur 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 does not occur in the mitochondria. 
D)  It is the main pathway that allows for synthesis of sugars from acetyl-CoA.

Question 19

The conversion of citrate to isocitrate is remarkable because

Accepted Answer

A)  it is a condensation reaction. 
B)  a chiral center is introduced in a molecule that did not have one previously. 
C)  a dehydration reaction is involved. 
D)  the enzyme that catalyzes it has very little specificity. 
A)  it is a condensation reaction. 
B)  a chiral center is introduced in a molecule that did not have one previously. 
C)  a dehydration reaction is involved. 
D)  the enzyme that catalyzes it has very little specificity.

Question 20

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

Exam 19: The Citric Acid Cycle

The reactions in which succinate is converted to oxaloacetate are,in order

Exhibit 19A The following compounds are all intermediates in the citric acid cycle. Refer to Exhibit 19A.Which intermediate becomes bonded to Coenzyme A during the cycle?

Which of the following describes a use for acetyl-CoA as an important intermediate in metabolism?

Which of these enzymes is most similar to pyruvate dehydrogenase?

In the conversion of succinyl-CoA to succinate,GTP is produced from GDP in a reaction in which the source of the added phosphate is

The citric acid cycle is the only metabolic pathway that can be used both as an anabolic and as a catabolic pathway.

Which of the following vitamins and enzyme cofactors are used by the pyruvate dehydrogenase complex during oxidative decarboxylation?

The only difference between succinate and fumarate is the geometry around their double bonds,one contains a cis double bond and the other contains a trans double bond.

Which of the following enzymes is not a control point of the citric acid cycle?

Which of the following is true regarding the control of pyruvate dehydrogenase?

The production of malate in the glyoxylate pathway is important,since it can be readily converted to phosphoenolpyruvate and then to sugars.

Thiamine pyrophosphate carries a ____ carbon unit.

Which of the following enzymes does not use NAD+ for oxidation?

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

Which enzyme catalyzes the reaction shown?

Which of the following enzymes is allosterically activated by NAD+?

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.

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

The conversion of citrate to isocitrate is remarkable because

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

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: 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

Which of the following enzymes does not use NAD⁺ for oxidation?

Which of the following enzymes is allosterically activated by NAD⁺?