Question 1

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  True

Question 2

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

Question 3

The compound uridine diphosphate glucose (UDPG) plays a role in

Accepted Answer

A)   glycogen breakdown.
B)   glycogen synthesis.
C)   glycolysis.
D)   gluconeogenesis. B

Question 4

Branching and debranching enzymes use the exact same mechanism to add and remove the branches of the glycogen polymer.

Accepted Answer

A) True 
 B)False

Question 5

When glycogen synthase is phosphorylated

Accepted Answer

A)   its activity decreases.
B)   its activity increases.
C)   its activity is unaffected.
D)   That enzyme doesn't get phosphorylated.

Question 6

Glycogen is mainly found in

Accepted Answer

A)   liver and muscle.
B)   liver and brain.
C)   muscle and brain.
D)   liver, muscle, and brain.

Question 7

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

Question 8

High concentrations of fructose-2,6-bisphopshate

Accepted Answer

A)   stimulate glycolysis and inhibit gluconeogenesis.
B)   inhibit glycolysis and stimulate gluconeogenesis.
C)   stimulate both glycolysis and gluconeogenesis.
D)   inhibit both glycolysis and gluconeogenesis.

Question 9

UDP-glucose pyrophosphorylase works by this mechanism:

Accepted Answer

A)   It adds a phosphate group to glucose from UTP, leaving behind UDP.
B)   It adds a UMP molecule to glucose-1-phosphate by splitting out pyrophosphate.
C)   It adds a pyrophosphate group to glucose, using UTP.
D)   It adds a UDP molecule to glucose by splitting out phosphate.

Question 10

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

Question 11

Where is the enzyme glucose-6-phosphatase located?

Accepted Answer

A)   cytosol
B)   mitochondria
C)   endoplasmic reticulum
D)   none of these

Question 12

Which of the following is true?

Accepted Answer

A)   Gluconeogenesis from pyruvate involves simple reversal of all of the glycolysis reactions, except for the reactions that consumed ATP during catabolism.
B)   Anabolic reactions are usually the reversal of catabolic ones
C)   In gluconeogenesis, the effective reversal of the glycolytic reactions of hexokinase and phosphofructokinase involve the same sugar molecules but not the exact set of substrates and products
D)   all of these are true

Question 13

Which nucleotide triphosphate is hydrolysed in the conversion of oxaloacetate to phosphoenolpyruvate?

Accepted Answer

A)   ATP
B)   GTP
C)   CTP
D)   UTP
E)   No nucleotide triphosphate is hydrolysed.

Question 14

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 15

The formation and breakdown of fructose 2,6-bisphosphate

Accepted Answer

A)   is catalyzed by the same protein dependant upon whether it is phosphorylated or not.
B)   is catalyzed by the same protein dependant allosteric regulators.
C)   is catalyzed by different proteins.

Question 16

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.

Question 17

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

Question 18

Glycogen phosphorylase

Accepted Answer

A)   exists in two forms, phosphorylase a and phosphorylase b
B)   responds differently to allosteric effectors in its phosphorylated and dephosphorylated forms
C)   both of these
D)   neither of these

Question 19

Which of the following molecules is not a product of the pentose phosphate pathway?

Accepted Answer

A)   NADPH
B)   ribose-5-phosphate
C)   glycerate-3-phosphate
D)   xylulose-5-phosphate

Question 20

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

Exam 18: Storage Mechanisms and Control in Carbohydrate Metabolism