Question 1

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.

Question 2

Glucose-6-phosphatase activity is found associated with the endoplasmic reticulum.

Accepted Answer

A) True 
 B)False

Question 3

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.

Question 4

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.

Question 5

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

Question 6

Which of the following statements concerning branched polymers like glycogen is false?

Accepted Answer

A)   Branched polymers are more accessible to enzymes since they bond more water.
B)   All of the reducing ends of the branched polymer are available to release glucose.
C)   All of the non-reducing ends of the branched polymer are available to release glucose.
D)   A branched polymer like glycogen is more compact and stores more glucose molecules in a given volume.

Question 7

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.

Question 8

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.

Question 9

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.

Question 10

Where is the enzyme glucose-6-phosphatase located?

Accepted Answer

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

Question 11

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 12

Which of the following is NOT a hormone involved in the control of carbohydrate metabolism?

Accepted Answer

A)   epinephrine
B)   glucagon
C)   insulin
D)   phosphofructokinase

Question 13

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.
E)   glycolysis

Question 14

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.

Question 15

The NADH used for the reduction reactions during gluconeogenesis usually come from this reaction:

Accepted Answer

A)   Gylceraldehyde-3-phosphate dehydrogenase.
B)   Malate dehydrogenase activity in the cytoplasm.
C)   Pyruvate carboxylase activity in the mitochondria.
D)   A variety of reactions which produce NADH in the mitochondria.
E)   None of these, since it is NAD+ that is used in gluconeogenesis.

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

Question 17

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 18

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

Accepted Answer

A)   glycogen breakdown.
B)   glycogen synthesis.
C)   glycolysis.
D)   gluconeogenesis.
E)   none of these

Question 19

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 20

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.

Exam 18: Storage Mechanisms and Control in Carbohydrate Metabolism

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

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

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

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Glucose-6-phosphatase activity is found associated with the endoplasmic reticulum.

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

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The enzyme pyruvate carboxylase

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Which of the following is NOT a hormone involved in the control of carbohydrate metabolism?

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The oxidative reactions of the pentose phosphate pathway

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The enzyme phosphopentose isomerase is characterized by all the following except

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The Cori cycle involves the following:

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The NADH used for the reduction reactions during gluconeogenesis usually come from this reaction:

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

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If you're running away from a bear,

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Which of the following statements concerning branched polymers like glycogen is false?

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Where is the enzyme glucose-6-phosphatase located?

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

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

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The enzyme glycogen phosphorylase catalyzes a reaction in

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

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

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