Question 1

Which of the following is NOT a characteristic of AGEs?

Accepted Answer

A)  AGEs means advanced glycation end products.
B)  AGEs generated by elevated blood glucose contribute to circulation,joint,and vision problems of diabetics.
C)  AGEs alter the function of the protein to which they are attached.
D)  AGEs form by enzyme-catalyzed Schiff base formation between sugars and proteins. D

Question 2

An individual with von Gierke's disease lacks the enzyme glucose-6-phosphatase,which is a liver enzyme used to maintain blood glucose.Which clinical feature is seen in patients with this disease?

Accepted Answer

A)  overweight
B)  weakness
C)  headache
D)  hypoglycemia D

Question 3

Limit dextrins are degraded by the action of a debranching enzyme that has 2 distinct enzymatic activities.Which enzymatic activities does it carry out?

Accepted Answer

A)  β-amylase;α(1→6) glucosidase
B)  oligo(α1,4→α1,4) glucanotransferase;α(1→6) glucosidase
C)  α-amylase;α(1→6) glucosidase
D)  β-amylase;oligo(α1,4→α1,4) glucanotransferase B

Question 4

How many ATP and GTP combined are required in gluconeogenesis for 2 pyruvate glucose?

Accepted Answer

A)  4
B)  5
C)  6
D)  7

Question 5

cAMP-dependent protein kinase phosphorylates and thus inhibits PFK-2.Which enzyme is simultaneously activated as a result of this inhibition?

Accepted Answer

A)  fructokinase
B)  glucose-6-phosphatase
C)  hexokinase
D)  F-2,6-BPase

Question 6

If NADPH is needed for biosynthetic reactions but ribose-5-P is not needed,which of the following best represents the net reaction of the pentose phosphate pathway?

Accepted Answer

A)  4 fruc-6-P + 2 glyceraldehyde-3-P→ 6 ribose-5-P
B)  3 gluc-6-P + 6 NADP→ 6 NADPH + 3 CO₂ + 2 fruc-6-P + 1 glyceraldehyde-3-P
C)  gluc-6-P + 2 NADP→ 2 NADPH + CO₂ + ribose-5-P
D)  gluc-6-P + 2 glyceraldehyde-3-P →3 ribose-5-P

Question 7

Which of the following CANNOT be used as a substrate for gluconeogenesis in the liver?

Accepted Answer

A)  alanine
B)  aspartic acid
C)  glycerol
D)  succinate

Question 8

Which of the following is NOT a characteristic of glucose-6-phosphate dehydrogenase?

Accepted Answer

A)  located in the mitochondria
B)  strongly inhibited by [NADPH]
C)  inhibited by fatty acid-CoA
D)  uses NADP+ as a coenzyme

Question 9

Which of the following is NOT a physiological change initiated by glucagon?

Accepted Answer

A)  activation of glycogenolysis in liver
B)  stimulation of liver gluconeogenesis
C)  long-term maintenance of steady-state levels of glucose in the blood stream
D)  activation of glycogenolysis in muscles

Question 10

Which 3 enzyme-regulated reactions of glycolysis are replaced by alternative reactions in the gluconeogenic pathway?

Accepted Answer

A)  glucokinase;PFK-1;pyruvate kinase
B)  phosphoglucoisomerase;PFK-1;pyruvate kinase
C)  PFK-1;triose phosphate isomerase;pyruvate kinase
D)  pyruvate carboxylase;PFK-1;glyceraldehyde-3-phosphate dehydrogenase

Question 11

Which molecule does pyruvate carboxylase consume in order to drive a carboxylation so that PEP carboxykinase could use the energy from decarboxylation to facilitate formation of PEP?

Accepted Answer

A)  NADH
B)  NADPH
C)  GTP
D)  ATP

Question 12

Which conditions trigger the conversion of pyruvate into OAA for gluconeogenesis?

Accepted Answer

A)  high levels of NADH and ATP
B)  high levels of NAD⁺ and acetyl CoA
C)  high levels of ATP and acetyl CoA
D)  high levels of ATP and NAD⁺

Question 13

Which of the following results when glucagon binds to its receptor?

Accepted Answer

A)  Glycolysis is activated.
B)  Protein synthesis is activated.
C)  Glycogen synthesis is inhibited.
D)  The citric acid cycle is inhibited.

Question 14

Which of the following enzyme-catalyzed steps requires energy input for the synthesis of glycogen?

Accepted Answer

A)  phosphoglucomutase
B)  UDP-glucose pyrophosphorylase
C)  glycogen synthase
D)  amylo-(1,4→1,6) -transglycosylase

Question 15

The pentose phosphate pathway is an important source of NADPH and for ribose-5-phosphate.Which of the following is NOT made from ribose-5-phosphate?

Accepted Answer

A)  ATP
B)  NAD⁺
C)  fatty acids
D)  CoA

Question 16

Which process occurs when a cell with the pentose phosphate pathway has need for more pentose phosphates,but no additional NADPH?

Accepted Answer

A)  Glucose-6-phosphate dehydrogenase is activated.
B)  The oxidative and non-oxidative enzymes of the pentose phosphate pathway are active.
C)  The non-oxidative enzymes produce pentose phosphates from fructose-6-phosphate and glyceraldehyde-3-phosphate.
D)  All enzymes of glycolysis and pentose phosphate pathway are activated.

Question 17

Which of these steps is NOT a component of the pyruvate carboxylase-catalyzed reaction?

Accepted Answer

A)  formation of N-carbonyl biotin
B)  attack of H₂CO3 on ATP
C)  formation of carbonyl phosphate
D)  C-3 carbanion of pyruvate attack on N-carbonyl biotin

Question 18

What is the endoplasmic reticulum-bound enzyme that hydrolyzes glucose-6-phosphate to glucose in liver?

Accepted Answer

A)  glucose-6-phosphatase
B)  glucose oxidase
C)  hexokinase
D)  phosphoglucomutase

Question 19

Which of the following is NOT a part of the transketolase-catalyzed reaction?

Accepted Answer

A)  formation of Schiff base intermediate of a new ketose
B)  b-cleavage of Schiff base intermediate to release a ketose
C)  active-site lysine formation of Schiff base with keto-carbonyl group
D)  Schiff base hydrated to ketose and enzyme

Question 20

Which glycolytic enzyme is analogous to the transaldolase-catalyzed activity?

Accepted Answer

A)  aldolase
B)  phosphoglucomutase
C)  enolase
D)  PFK-1

Exam 21: Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway