Question 1

The oxidative reactions of the pentose phosphate pathway

Accepted Answer

A)  produce NADPH rather than NADH. 
B)  require biotin. 
C)  require coenzyme A. 
D)  require thiamine pyrophosphate. 
A)  produce NADPH rather than NADH. 
B)  require biotin. 
C)  require coenzyme A. 
D)  require thiamine pyrophosphate.

Question 2

The activity of the enzyme fructose 1,6- bis phosphatase is

Accepted Answer

A)  inhibited by ATP. 
B)  stimulated by AMP. 
C)  inhibited by fructose 2,6- bis phosphate. 
D)  not subject to allosteric control. 
A)  inhibited by ATP. 
B)  stimulated by AMP. 
C)  inhibited by fructose 2,6- bis phosphate. 
D)  not subject to allosteric control.

Question 3

Hemolytic anemia is associated with the pentose phosphate pathway because:

Accepted Answer

A)  a deficiency of this pathway leads to a lack of NADPH in red blood cells 
B)  NADPH is required to reduce glutathione 
C)  Red blood cells have minimal resources for maintaining an oxidative balance 
D)  all of these 
A)  a deficiency of this pathway leads to a lack of NADPH in red blood cells 
B)  NADPH is required to reduce glutathione 
C)  Red blood cells have minimal resources for maintaining an oxidative balance 
D)  all of these

Question 4

Identify the enzyme that catalyzes the isomerization of glucose-1-phosphate to glucose 6-phosphate.

Accepted Answer

A)  Phosphogluconolactonase 
B)  Phosphoglucoisomerase 
C)  Phosphoglucokinase 
D)  Phosphoglucomutase 
A)  Phosphogluconolactonase 
B)  Phosphoglucoisomerase 
C)  Phosphoglucokinase 
D)  Phosphoglucomutase

Question 5

How many ATP equivalents are expended to convert 2 pyruvates to 1 glucose?

Accepted Answer

A)  2 
B)  4 
C)  6 
D)  8 
A)  2 
B)  4 
C)  6 
D)  8

Question 6

Which of the following hormone's main function is to raise the level of blood glucose?

Accepted Answer

A)  epinephrine 
B)  insulin 
C)  glucagon 
D)  none of these raises blood glucose 
A)  epinephrine 
B)  insulin 
C)  glucagon 
D)  none of these raises blood glucose

Question 7

If you're running away from a bear,

Accepted Answer

A)  both your liver cells and my leg muscle cells will be running glycolysis. 
B)  both your liver cells and my leg muscle cells will be running gluconeogenesis. 
C)  your liver cells will be running gluconeogenesis and your leg muscle cells will be running glycolysis. 
D)  your liver cells will be running glycolysis and your leg muscle cells will be running gluconeogenesis. 
A)  both your liver cells and my leg muscle cells will be running glycolysis. 
B)  both your liver cells and my leg muscle cells will be running gluconeogenesis. 
C)  your liver cells will be running gluconeogenesis and your leg muscle cells will be running glycolysis. 
D)  your liver cells will be running glycolysis and your leg muscle cells will be running gluconeogenesis.

Question 8

Generally speaking, the same mechanisms that activate glycogen phosphorylase will turn off glycogen synthase.

Accepted Answer

A) True 
 B)False

Question 9

The first reaction of gluconeogenesis is

Accepted Answer

A)  an oxidative decarboxylation 
B)  a carboxylation 
C)  a redox reaction 
D)  a phosphate transfer 
A)  an oxidative decarboxylation 
B)  a carboxylation 
C)  a redox reaction 
D)  a phosphate transfer

Question 10

Gluconeogenesis differs from glycolysis because

Accepted Answer

A)  the irreversible steps of glycolysis are bypassed 
B)  different enzymes are involved 
C)  biotin is required for gluconeogenesis and not for glycolysis 
D)  all of these 
E)  none of these 
A)  the irreversible steps of glycolysis are bypassed 
B)  different enzymes are involved 
C)  biotin is required for gluconeogenesis and not for glycolysis 
D)  all of these 
E)  none of these

Question 11

During the pentose phosphate pathway (glucose-6-P → ribose-5-P), is there a net oxidation of the substrate carbon atoms?

Accepted Answer

A)  Yes. 
B)  No. 
C)  It depends on whether the process is under aerobic or anaerobic conditions. 
D)  It depends on the species doing the process. 
E)  It depends on whether the glucose goes through the oxidative part of the pathway or not. 
A)  Yes. 
B)  No. 
C)  It depends on whether the process is under aerobic or anaerobic conditions. 
D)  It depends on the species doing the process. 
E)  It depends on whether the glucose goes through the oxidative part of the pathway or not.

Question 12

In one normal cycle of the pentose phosphate pathway, the enzyme transaldolase is used twice and the enzyme transketolase is used once.

Accepted Answer

A) True 
 B)False

Question 13

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

Accepted Answer

A)  glycogen phosphorylase 
B)  debranching enzyme 
C)  phosphoglucomutase 
D)  glycogen synthase 
E)  None of these because there are no α (1 → 6) bonds in glycogen. 
A)  glycogen phosphorylase 
B)  debranching enzyme 
C)  phosphoglucomutase 
D)  glycogen synthase 
E)  None of these because there are no α (1 → 6) bonds in glycogen.

Question 14

Glycolysis that starts with glycogen instead of glucose can be considered to have a higher energy yield because:

Accepted Answer

A)  Phosphorolysis reactions cleave bonds with phosphate instead of water. 
B)  Phosphorylase is a better enzyme than hexokinase 
C)  Phosphorylase produces a glucose phosphate without spending an ATP to do it 
D)  All of these 
E)  None of these is true because glycolysis starting from glycogen does not have a higher energy yield 
A)  Phosphorolysis reactions cleave bonds with phosphate instead of water. 
B)  Phosphorylase is a better enzyme than hexokinase 
C)  Phosphorylase produces a glucose phosphate without spending an ATP to do it 
D)  All of these 
E)  None of these is true because glycolysis starting from glycogen does not have a higher energy yield

Question 15

When glycogen phosphorylase is phosphorylated

Accepted Answer

A)  its activity decreases. 
B)  its activity increases. 
C)  its activity is unaffected. 
D)  none of these because that enzyme doesn't get phosphorylated. 
A)  its activity decreases. 
B)  its activity increases. 
C)  its activity is unaffected. 
D)  none of these because that enzyme doesn't get phosphorylated.

Question 16

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 17

Control of the entry of glucose or fructose into the oxidative portions of the pentose phosphate pathway is mostly dependent on a cell's need for NADPH, rather than on the cell's need for pentoses.

Accepted Answer

A) True 
 B)False

Question 18

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 19

Hydrolysis of pyrophosphate is an important energy driving force in the synthesis of glycogen.

Accepted Answer

A) True 
 B)False

Question 20

In the process of substrate cycling

Accepted Answer

A)  different organs are responsible for the synthesis and breakdown of the same substance. 
B)  there is no net consumption of ATP. 
C)  allosteric control is not involved. 
D)  different enzymes, subject to independent control, are responsible for the synthesis and breakdown of the same substance. 
A)  different organs are responsible for the synthesis and breakdown of the same substance. 
B)  there is no net consumption of ATP. 
C)  allosteric control is not involved. 
D)  different enzymes, subject to independent control, are responsible for the synthesis and breakdown of the same substance.

Exam 18: Storage Mechanisms and Control in Carbohydrate Metabolism

The oxidative reactions of the pentose phosphate pathway

The activity of the enzyme fructose 1,6- bis phosphatase is

Hemolytic anemia is associated with the pentose phosphate pathway because:

Identify the enzyme that catalyzes the isomerization of glucose-1-phosphate to glucose 6-phosphate.

How many ATP equivalents are expended to convert 2 pyruvates to 1 glucose?

Which of the following hormone's main function is to raise the level of blood glucose?

If you're running away from a bear,

Generally speaking, the same mechanisms that activate glycogen phosphorylase will turn off glycogen synthase.

The first reaction of gluconeogenesis is

Gluconeogenesis differs from glycolysis because

During the pentose phosphate pathway (glucose-6-P → ribose-5-P), is there a net oxidation of the substrate carbon atoms?

In one normal cycle of the pentose phosphate pathway, the enzyme transaldolase is used twice and the enzyme transketolase is used once.

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

Glycolysis that starts with glycogen instead of glucose can be considered to have a higher energy yield because:

When glycogen phosphorylase is phosphorylated

A characteristic of the reaction catalyzed by transaldolase is

Control of the entry of glucose or fructose into the oxidative portions of the pentose phosphate pathway is mostly dependent on a cell's need for NADPH, rather than on the cell's need for pentoses.

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

Hydrolysis of pyrophosphate is an important energy driving force in the synthesis of glycogen.

In the process of substrate cycling

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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