Question 1

What kind of enzyme catalyzes the following reaction?
Ribose-5-P ↔ ribulose-5-P

Accepted Answer

A)  transketolase 
B)  epimerase 
C)  transaldolase 
D)  isomerase 
A)  transketolase 
B)  epimerase 
C)  transaldolase 
D)  isomerase

Question 2

The activity of glycogen phosphorylase depends on

Accepted Answer

A)  allosteric control 
B)  covalent modification 
C)  both of these 
D)  neither of these 
A)  allosteric control 
B)  covalent modification 
C)  both of these 
D)  neither of these

Question 3

Which of the following reactions occur when a single glucose residue is transferred from UDP-glucose to a growing glycogen molecule?

Accepted Answer

A)  UDP is released. 
B)  The glucose can be attached to a #4 carbon atom in the glycogen molecule. 
C)  UDP is released and the glucose is attached to a #4 carbon. 
D)  All of these events can occur when a single glucose residue is added. 
A)  UDP is released. 
B)  The glucose can be attached to a #4 carbon atom in the glycogen molecule. 
C)  UDP is released and the glucose is attached to a #4 carbon. 
D)  All of these events can occur when a single glucose residue is added.

Question 4

The enzyme glucose-6-phosphatase is only found in cells which have this function or ability:

Accepted Answer

A)  Ability to utilize glucose anaerobically. 
B)  Ability to replenish the levels of glucose in the blood. 
C)  Glycogen storage. 
D)  Ability to produce lactic acid as an end product of metabolism. 
E)  Glucose-6-phosphatase activity is found in almost all types of cells. 
A)  Ability to utilize glucose anaerobically. 
B)  Ability to replenish the levels of glucose in the blood. 
C)  Glycogen storage. 
D)  Ability to produce lactic acid as an end product of metabolism. 
E)  Glucose-6-phosphatase activity is found in almost all types of cells.

Question 5

Which enzyme is used in gluconeogenesis, but NOT in glycolysis?

Accepted Answer

A)  PEP carboxykinase 
B)  enolase 
C)  phosphohexose isomerase 
D)  3-phosphoglycerate dehydrogenase 
A)  PEP carboxykinase 
B)  enolase 
C)  phosphohexose isomerase 
D)  3-phosphoglycerate dehydrogenase

Question 6

The enzyme that catalyzes the interconversion of glucose-1-phosphate and glucose-6-phosphate is

Accepted Answer

A)  a hydrolase. 
B)  a phosphorylase. 
C)  a mutase. 
D)  a dehydrogenase. 
E)  an epimerase 
A)  a hydrolase. 
B)  a phosphorylase. 
C)  a mutase. 
D)  a dehydrogenase. 
E)  an epimerase

Question 7

In gluconeogenesis, the initial reaction converts pyruvate to

Accepted Answer

A)  oxaloacetate 
B)  acetyl-CoA 
C)  phosphoenolpyruvate 
D)  lactate 
E)  glucose 
A)  oxaloacetate 
B)  acetyl-CoA 
C)  phosphoenolpyruvate 
D)  lactate 
E)  glucose

Question 8

If an individual lacked the debranching enzyme, the effect would be:

Accepted Answer

A)  the individual could not make glycogen 
B)  the individual could make glycogen but not store it 
C)  the individual would not be able to utilize any glucose from glycogen 
D)  the individual would not be able to completely break down a glycogen molecule 
E)  none of these 
A)  the individual could not make glycogen 
B)  the individual could make glycogen but not store it 
C)  the individual would not be able to utilize any glucose from glycogen 
D)  the individual would not be able to completely break down a glycogen molecule 
E)  none of these

Question 9

Which of the following statements concerning the initial phase of the pentose phosphate pathway is false ?

Accepted Answer

A)  A CO2 molecule is released from glucose. 
B)  Two molecules of NADPH are produced per glucose. 
C)  Ribulose-5-phosphate is produced by an oxidative decarboxylation of 6-phosphogluconate. 
D)  The process reduces glucose-6-phosphate. 
A)  A CO2 molecule is released from glucose. 
B)  Two molecules of NADPH are produced per glucose. 
C)  Ribulose-5-phosphate is produced by an oxidative decarboxylation of 6-phosphogluconate. 
D)  The process reduces glucose-6-phosphate.

Question 10

The Cori cycle involves the following:

Accepted Answer

A)  Conversion of lactate produced in the liver by regeneration of glucose in the muscle. 
B)  Conversion of pyruvate produced in the muscle by regeneration of glucose in the liver. 
C)  Conversion of lactate produced in the muscle by regeneration of glucose in the liver. 
D)  Conversion of NADH produced in the muscle by regeneration of glucose in the liver. 
E)  The Cori cycle involves a different pathway from any of these. 
A)  Conversion of lactate produced in the liver by regeneration of glucose in the muscle. 
B)  Conversion of pyruvate produced in the muscle by regeneration of glucose in the liver. 
C)  Conversion of lactate produced in the muscle by regeneration of glucose in the liver. 
D)  Conversion of NADH produced in the muscle by regeneration of glucose in the liver. 
E)  The Cori cycle involves a different pathway from any of these.

Question 11

Which of the following best describes how liver supplies other tissues with the glucose it releases from its stored glycogen?

Accepted Answer

A)  It releases short chains of glucose residues into the blood. 
B)  It releases glucose-1-phosphate into the blood. 
C)  It releases glucose-6-phosphate into the blood. 
D)  It releases glucose into the blood. 
E)  It releases glucose in the form of lipopolysaccharides 
A)  It releases short chains of glucose residues into the blood. 
B)  It releases glucose-1-phosphate into the blood. 
C)  It releases glucose-6-phosphate into the blood. 
D)  It releases glucose into the blood. 
E)  It releases glucose in the form of lipopolysaccharides

Question 12

The primary function of the pentose phosphate pathway is

Accepted Answer

A)  to synthesize NAD+ and pentose phosphates. 
B)  to synthesize NADPH and pentose phosphates. 
C)  to produce NADH. 
D)  to convert pentose phosphates to metabolic intermediates for oxidative phosphorylation. 
A)  to synthesize NAD+ and pentose phosphates. 
B)  to synthesize NADPH and pentose phosphates. 
C)  to produce NADH. 
D)  to convert pentose phosphates to metabolic intermediates for oxidative phosphorylation.

Question 13

The enzyme pyruvate carboxylase

Accepted Answer

A)  is not subject to allosteric control 
B)  requires biotin for activity 
C)  catalyzes a reaction that does not require ATP 
D)  is inhibited by acetyl-CoA 
A)  is not subject to allosteric control 
B)  requires biotin for activity 
C)  catalyzes a reaction that does not require ATP 
D)  is inhibited by acetyl-CoA

Question 14

Glycogen loading is particularly advantageous for providing energy for long distance athletic events, such as running the marathon.

Accepted Answer

A) True 
 B)False

Question 15

Which of the following is not a control mechanism for glycogen phosphorylase?

Accepted Answer

A)  Covalent modification. 
B)  Inhibition by glucose. 
C)  Subunit association and dissociation. 
D)  Allosteric stimulation by AMP. 
E)  All of these mechanisms regulate the activity of glycogen synthase. 
A)  Covalent modification. 
B)  Inhibition by glucose. 
C)  Subunit association and dissociation. 
D)  Allosteric stimulation by AMP. 
E)  All of these mechanisms regulate the activity of glycogen synthase.

Question 16

The conversion of ribulose 5-phosphate to xylulose 5-phosphate is

Accepted Answer

A)  a dehydration 
B)  an oxidation 
C)  a reduction 
D)  an epimerization 
A)  a dehydration 
B)  an oxidation 
C)  a reduction 
D)  an epimerization

Question 17

In the Cori cycle

Accepted Answer

A)  lactic acid is transported from the liver to muscle by the blood. 
B)  lactic acid is transported from the liver to the kidneys by the blood. 
C)  glycolysis takes place in muscle and gluconeogenesis in the liver. 
D)  glycolysis takes place in the liver and gluconeogenesis in muscle. 
E)  none of these 
A)  lactic acid is transported from the liver to muscle by the blood. 
B)  lactic acid is transported from the liver to the kidneys by the blood. 
C)  glycolysis takes place in muscle and gluconeogenesis in the liver. 
D)  glycolysis takes place in the liver and gluconeogenesis in muscle. 
E)  none of these

Question 18

The same enzymes are responsible for covalent modifications of both glycogen synthase and glycogen phosphorylase in regulating their activity.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following statements concerning biotin and gluconeogenesis is false ?

Accepted Answer

A)  Biotin is used to add CO2 to certain intermediates in gluconeogenesis. 
B)  CO2 is incorporated into the glucose product. 
C)  Biotin is capable of binding covalently to CO2. 
D)  Biotin helps synthesize an important precursor of phosphoenolpyruvate. 
E)  ATP hydrolysis is required to attach CO2 to biotin. 
A)  Biotin is used to add CO2 to certain intermediates in gluconeogenesis. 
B)  CO2 is incorporated into the glucose product. 
C)  Biotin is capable of binding covalently to CO2. 
D)  Biotin helps synthesize an important precursor of phosphoenolpyruvate. 
E)  ATP hydrolysis is required to attach CO2 to biotin.

Question 20

What kind of reaction is used to release glucose units from glycogen?

Accepted Answer

A)  hydrolysis 
B)  phosphorolysis 
C)  dehydration 
D)  oxidation 
E)  dehydrogenation 
A)  hydrolysis 
B)  phosphorolysis 
C)  dehydration 
D)  oxidation 
E)  dehydrogenation

Exam 18: Storage Mechanisms and Control in Carbohydrate Metabolism

What kind of enzyme catalyzes the following reaction? Ribose-5-P ↔ ribulose-5-P

The activity of glycogen phosphorylase depends on

Which of the following reactions occur when a single glucose residue is transferred from UDP-glucose to a growing glycogen molecule?

The enzyme glucose-6-phosphatase is only found in cells which have this function or ability:

Which enzyme is used in gluconeogenesis, but NOT in glycolysis?

The enzyme that catalyzes the interconversion of glucose-1-phosphate and glucose-6-phosphate is

In gluconeogenesis, the initial reaction converts pyruvate to

If an individual lacked the debranching enzyme, the effect would be:

Which of the following statements concerning the initial phase of the pentose phosphate pathway is false ?

The Cori cycle involves the following:

Which of the following best describes how liver supplies other tissues with the glucose it releases from its stored glycogen?

The primary function of the pentose phosphate pathway is

The enzyme pyruvate carboxylase

Glycogen loading is particularly advantageous for providing energy for long distance athletic events, such as running the marathon.

Which of the following is not a control mechanism for glycogen phosphorylase?

The conversion of ribulose 5-phosphate to xylulose 5-phosphate is

In the Cori cycle

The same enzymes are responsible for covalent modifications of both glycogen synthase and glycogen phosphorylase in regulating their activity.

Which of the following statements concerning biotin and gluconeogenesis is false ?

What kind of reaction is used to release glucose units from glycogen?

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

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism Cellular Signaling

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