Question 1

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 2

Which of the following mechanisms can be used to regulate metabolic pathways?

Accepted Answer

A)  Allosteric activators and inhibitors. 
B)  Covalent modifications of enzymes. 
C)  Use of separate enzymes at a given point in the forward and backward pathways. 
D)  Regulation of the genes for the enzymes used in the pathway. 
E)  All of these are used to regulate metabolism. 
A)  Allosteric activators and inhibitors. 
B)  Covalent modifications of enzymes. 
C)  Use of separate enzymes at a given point in the forward and backward pathways. 
D)  Regulation of the genes for the enzymes used in the pathway. 
E)  All of these are used to regulate metabolism.

Question 3

In addition to pentoses,the pentose phosphate pathway involves sugars of all these sizes except:

Accepted Answer

A)  3 carbons 
B)  4 carbons 
C)  6 carbons 
D)  7 carbons 
E)  All of these sizes are used in this pathway. 
A)  3 carbons 
B)  4 carbons 
C)  6 carbons 
D)  7 carbons 
E)  All of these sizes are used in this pathway.

Question 4

The regulatory enzymes in gluconeogenesis are

Accepted Answer

A)  hexokinase, phosphofructokinase, and pyruvate kinase 
B)  glucose-6-kinase, aldolase, and enolase 
C)  glucose-6-phosphatase, fructose-1,6-bisphosphatase, pyruvate carboxylase, and phosphoenolpyruvate carboxykinase 
D)  pyruvate carboxylase, aldolase, and phosphofructokinase 
A)  hexokinase, phosphofructokinase, and pyruvate kinase 
B)  glucose-6-kinase, aldolase, and enolase 
C)  glucose-6-phosphatase, fructose-1,6-bisphosphatase, pyruvate carboxylase, and phosphoenolpyruvate carboxykinase 
D)  pyruvate carboxylase, aldolase, and phosphofructokinase

Question 5

Which of the following molecules does not directly regulate the activity of glycogen synthase?

Accepted Answer

A)  Glucose 
B)  Glucose-6-phosphate 
C)  AMP 
D)  ATP 
E)  Concentration of all of these affects glycogen synthase. 
A)  Glucose 
B)  Glucose-6-phosphate 
C)  AMP 
D)  ATP 
E)  Concentration of all of these affects glycogen synthase.

Question 6

A characteristic of the reaction catalyzed by transaldolase is

Accepted Answer

A)  transfer of a three-carbon unit 
B)  transfer of a two-carbon unit 
C)  a requirement for TPP as a coenzyme 
D)  an energy requirement for oxidative decarboxylation 
A)  transfer of a three-carbon unit 
B)  transfer of a two-carbon unit 
C)  a requirement for TPP as a coenzyme 
D)  an energy requirement for oxidative decarboxylation

Question 7

Glycogen synthase and glycogen phosphorylase

Accepted Answer

A)  are modified by the same enzymes 
B)  are not subject to allosteric control 
C)  are not subject to covalent modification 
D)  none of these 
A)  are modified by the same enzymes 
B)  are not subject to allosteric control 
C)  are not subject to covalent modification 
D)  none of these

Question 8

The molecule fructose 2,6-bisphosphate:

Accepted Answer

A)  is an intermediate in glycolysis 
B)  is an intermediate of gluconeogenesis but not glycolysis 
C)  does not exist 
D)  is an important regulatory molecule in the control of carbohydrate metabolism 
E)  none of these 
A)  is an intermediate in glycolysis 
B)  is an intermediate of gluconeogenesis but not glycolysis 
C)  does not exist 
D)  is an important regulatory molecule in the control of carbohydrate metabolism 
E)  none of these

Question 9

Gluconeogenesis is the synthesis of

Accepted Answer

A)  glucose from non-carbohydrate precursors 
B)  glycogen from glucose 
C)  pyruvate from glucose 
D)  fatty acids from glucose 
A)  glucose from non-carbohydrate precursors 
B)  glycogen from glucose 
C)  pyruvate from glucose 
D)  fatty acids from glucose

Question 10

In gluconeogenesis,the initial reaction converts pyruvate to

Accepted Answer

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

Question 11

The process called substrate cycling is used to describe this process:

Accepted Answer

A)  Freely reversible reactions. 
B)  Recycling of vitamins as catalysts in metabolism 
C)  Situations where there are two different enzymes used to reverse a specific step in a metabolic pathway. 
D)  Metabolic pathways which run in cycles and regenerate the initial molecule. 
E)  None of these answers describes substrate cycling. 
A)  Freely reversible reactions. 
B)  Recycling of vitamins as catalysts in metabolism 
C)  Situations where there are two different enzymes used to reverse a specific step in a metabolic pathway. 
D)  Metabolic pathways which run in cycles and regenerate the initial molecule. 
E)  None of these answers describes substrate cycling.

Question 12

All of the following sugar rearrangements are part of the pentose phosphate pathway,except.

Accepted Answer

A)  C5 + C5 C7 + C3 
B)  C5 + C5 C6 + C4 
C)  C7 + C3 C6 + C4 
D)  C5 + C4 C6 + C3 
E)  All of these rearrangements occur in the pentose phosphate pathway. 
A)  C5 + C5 C7 + C3 
B)  C5 + C5 C6 + C4 
C)  C7 + C3 C6 + C4 
D)  C5 + C4 C6 + C3 
E)  All of these rearrangements occur in the pentose phosphate pathway.

Question 13

The enzyme phosphopentose isomerase is characterized by all the following except

Accepted Answer

A)  it catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate 
B)  there is no requirement for ATP 
C)  it converts a ketose to an aldose 
D)  it catalyzes an inversion of configuration at carbon-3 
A)  it catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate 
B)  there is no requirement for ATP 
C)  it converts a ketose to an aldose 
D)  it catalyzes an inversion of configuration at carbon-3

Question 14

Starting from glucose and UTP and ATP,how many high-energy bonds are broken/consumed to add that glucose to a glycogen molecule?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  The answer cannot be determined form the information given. 
A)  1 
B)  2 
C)  3 
D)  4 
E)  The answer cannot be determined form the information given.

Question 15

Which of the following is not an advantage that glycogen provides to muscle cells in which it is stored?

Accepted Answer

A)  It is available for quick energy spurts. 
B)  It requires no energy to mobilize the glucose residues for metabolism. 
C)  It gives anaerobic metabolism a boost. 
D)  It draws more water into the cells than glucose would. 
E)  All of these are advantages that glycogen provides to muscle cells. 
A)  It is available for quick energy spurts. 
B)  It requires no energy to mobilize the glucose residues for metabolism. 
C)  It gives anaerobic metabolism a boost. 
D)  It draws more water into the cells than glucose would. 
E)  All of these are advantages that glycogen provides to muscle cells.

Question 16

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 17

The enzyme glycogen phosphorylase catalyzes a reaction in

Accepted Answer

A)  the formation of glycogen from glucose. 
B)  glycogen breakdown. 
C)  gluconeogenesis. 
D)  the pentose phosphate pathway. 
A)  the formation of glycogen from glucose. 
B)  glycogen breakdown. 
C)  gluconeogenesis. 
D)  the pentose phosphate pathway.

Question 18

In which cellular compartment is pyruvate carboxylase found?

Accepted Answer

A)  cytosol 
B)  mitochondria 
C)  endoplasmic reticulum 
D)  nucleus 
A)  cytosol 
B)  mitochondria 
C)  endoplasmic reticulum 
D)  nucleus

Question 19

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 20

Which enzyme cleaves the a(1 6) bonds in glycogen?

Accepted Answer

A)  glycogen phosphorylase 
B)  debranching enzyme 
C)  phosphoglucomutase 
D)  glycogen synthase 
E)  There are no a(1 6) bonds in glycogen. 
A)  glycogen phosphorylase 
B)  debranching enzyme 
C)  phosphoglucomutase 
D)  glycogen synthase 
E)  There are no a(1 6) bonds in glycogen.

Exam 18: Storage Mechanisms and Control in Carbohydrate Metabolism

The primary function of the pentose phosphate pathway is

Which of the following mechanisms can be used to regulate metabolic pathways?

In addition to pentoses,the pentose phosphate pathway involves sugars of all these sizes except:

The regulatory enzymes in gluconeogenesis are

Which of the following molecules does not directly regulate the activity of glycogen synthase?

A characteristic of the reaction catalyzed by transaldolase is

Glycogen synthase and glycogen phosphorylase

The molecule fructose 2,6-bisphosphate:

Gluconeogenesis is the synthesis of

In gluconeogenesis,the initial reaction converts pyruvate to

The process called substrate cycling is used to describe this process:

All of the following sugar rearrangements are part of the pentose phosphate pathway,except.

The enzyme phosphopentose isomerase is characterized by all the following except

Starting from glucose and UTP and ATP,how many high-energy bonds are broken/consumed to add that glucose to a glycogen molecule?

Which of the following is not an advantage that glycogen provides to muscle cells in which it is stored?

What kind of enzyme catalyzes the following reaction? ribose-5-P « ribulose-5-P

The enzyme glycogen phosphorylase catalyzes a reaction in

In which cellular compartment is pyruvate carboxylase found?

The activity of glycogen phosphorylase depends on

Which enzyme cleaves the a(1 6) bonds in 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: 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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