Study Questions

Q1. Choose the ONE correct answer

1. Which of the following enzyme catalyzes the first step of glycolysis?

A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
2. Which of the following statements is true for anabolic pathways only?
A. Their irreversible (nonequilibrium) reactions are regulated.
B. They are called cycles if they regenerate an intermediate.
C. They are convergent and generate a few simple products.
D. They are synthetic and require energy.
E. They typically require oxidized coenzymes
3. The reaction catalyzed by phosphofructokinase-1:
A. is activated by high concentrations of ATP and citrate.
B. uses fructose 1-phosphate as substrate.
C. is the rate-limiting reaction of the glycolytic pathway.
D. is near equilibrium in most tissues.
E. is inhibited by fructose 2,6-bisphosphate.
4. 43-year-old man presented with symptoms of weakness, fatigue, shortness of breath, and dizziness. His
hemoglobin level was less than 7 g/dl (normal for a male being greater than 13.5 g/dl). Red blood cells
isolated from the patient showed abnormally low level of lactate production. A deficiency of which one
of the following enzymes would be the most likely cause of this patient’s anemia?
A. Phosphoglucose isomerase
B. Phosphofructokinase
C. Pyruvate kinase
D. Hexokinase
E. Lactate dehydrogenase

5. Which of the following statements is true for anabolic pathways only?

A. Their irreversible (non-equilibrium) reactions are regulated.
B. They are called cycles if they regenerate an intermediate.
C. The y are convergent and generate a few simple products.
D. They are synthetic and require energy.
E. They typically require oxidized coenzymes.
6. Which of the following glucose transporter (GLUT) is important in insulin-dependent glucose uptake?
A. GLUT1
B. GLUT2
C. GLUT3
D. GLUT4
7. Which of the following glucose transporter (GLUT) is present in the beta cells of the pancreas?
A. GLUT1
B. GLUT2
C. GLUT3
D. GLUT4
8. Which of the following glucose transporter (GLUT) is important in fructose transport in the intestine?
A. GLUT1
B. GLUT3
C. GLUT5
D. GLUT7
9. Which of the following metabolite negatively regulates pyruvate kinase?
A. Fructose-1,6-Bisphosphate
B. Citrate
C. Acetyl CoA
D. Alanine
10. In absence of oxygen, pyruvate is converted into lactate in muscle because
A. Lactate is the substrate from the downstream pathway
B. Lactate acts as a substrate for the formation of amino acid
C. during the product of lactate two ATP are produced
D. during lactate formation, NADH is reconverted into NAD.
11. Which of the following glycolytic enzyme is inhibited by the accumulation of long-chain fatty acid in
the liver?
A. Hexokinase
B. Glucokinase
C. Phosphofructokinase
D. Pyruvate kinase
12. Which of the following statement related to phosphofructokinase-I is false:
A. PFK-2 is the isoenzyme of PFK-1 that is present in the liver
B. PFK-1 is activated by AMP whereas inhibited by ATP and citrate
C. The binding of ATP to PFK-1 induces the conformation change from R to T state
D. PFK-1 is regulated by posttranslational modification such as phosphorylation
13. Which of the following statement about Phosphofructokinase-2 (PFK-2) is false?
A. PFK-2 is a bifunctional enzyme having a kinase domain, phosphatase domain, and a regulatory
domain
B. Activated protein kinase A phosphorylates PFK-2 and activates the phosphatase domain
C. PFK-2 catalyzes the conversion of fructose-6-phosphate to fructose 2-6 bisphosphate
D. PFK-2 phosphatase activity is activated by the insulin signaling pathway.

14. Which of the following hormone decreases blood glucose and increases the uptake of glucose in various
tissues like skeletal muscle, and adipose tissues?
A. Glucagon
B. Epinephrine
C. Cortisol
D. Insulin
15. Which of the following statement is true?
a) Glycolysis occurs only in mammalian cells
b) Glycolysis occurs in mitochondria
c) Glycolysis occurs in the presence and absence of oxygen
d) Glycolysis occurs when ATP concentration is high.
16. What is the rate-limiting step in glycolysis?
a) Hexokinase
b) Phosphohexose isomerase
c) Glyceraldehyde-3-phosphate dehydrogenase
d) Enolase
17. The net gain of ATP during the conversion of glucose to pyruvate is:
a) 1 ATP
b) 2 ATP
c) 1 ATP +1 GTP
d) 4 ATP
18. During the conversion of glucose to pyruvate, two NADH molecules are generated.
Which of the following steps generates NADH?
a) Conversion of fructose-6-phosphate to fructose-1-6-bisphosphate
b) Conversion of glyceraldehydes-3-phosphate to 1-3-bisphosphoglycerate
c) Conversion of 3-phosphoglycerate to 2-phosphoglycerate
d) Conversion of phosphoenolpyruvate to pyruvate
19. What is the committed step in glycolysis?
a) Conversion of glucose to glucose-6-phosphate
b) Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate
c) Conversion of glyceraldehydes-3-phosphate to 1-3-bisphosphoglycerate
d) Conversion of 3-phosphoglycerate to 2-phosphoglycerate
20. Glycolysis consists of three irreversible steps. Which of the following enzyme-catalyzed reaction are not
irreversible steps in glycolysis?
a) Hexokinase
b) Phosphofructokinase
c) Glyceraldehyde-3-phosphate kinase
d) Pyruvate kinase
21. The following are the negative regulators of phosphofructokinase except
a) ATP
b) AMP
c) Citrate
d) pH
22. Which of the following step is inhibited by sodium fluoride?
a) Glyceraldehyde-3-phosphate dehydrogenase
b) 3-phosphoglycerate mutase
c) Enolase
b) AMP
23. Which of the following step is inhibited during arsenate poisoning?
a) Glyceraldehyde-3-phosphate dehydrogenase
b) 3-phosphoglycerate mutase
c) Enolase
d) Pyruvate kinase
24. Which of the following enzyme catalyzes the conversion of pyruvate to lactate?
a) Pyruvate reductase
b) Lactate reductase
c) Lactate dehydrogenase
d) Pyruvate dehydrogenase
25. Glucokinase is an isoenzyme of hexokinase that has high Km and Vmax.
Which of the following organ expresses glucokinase?
a) Kidney
b) Muscle
c) Liver
d) Brain
26. Gluconeogenesis is the production of glucose from non-carbohydrate molecules.
Which of the following is not a substrate for gluconeogenesis?
a) Lactate
b) Alanine
c) Glycerol
d) Acetyl CoA
27. Gluconeogenesis occurs in the liver and kidneys.
Which is of the following enzyme are important for gluconeogenesis and are expressed exclusively in
these tissues?
a) Glucose-6-phosphatase
b) Fructose-1,6-Bisphosphatase
c) Phosphoenolpyruvate carboxykinase
d) Pyruvate carboxylase
28. During gluconeogenesis, the three irreversible steps of glycolysis have to be bypassed. The first step is
the conversion of pyruvate to phosphoenolpyruvate.
Which of the following statement is false regarding the reaction step?
A. This reaction involves a two-step process catalyzed by pyruvate carboxylase and
phosphoenolpyruvate carboxykinase
B. Conversion of oxaloacetate from pyruvate occurs in mitochondria and shuttled into the cytosol.
C. Formation of phosphoenolpyruvate requires both ATP and GTP as an energy source.
D. Acetyl CoA is an activator of the enzyme pyruvate carboxylase.
29. During gluconeogenesis, the three irreversible steps of glycolysis have to be bypassed. The final step is
the conversion of glucose-6-P to glucose which is catalyzed by glucose-6-phosphatase.
Which of the following statement is true about the reaction step?
a) Conversion of glucose-6-phosphate to glucose releases one ATP molecule
b) It is a highly active enzyme in skeletal muscle
c) Defect in glucose-6-phosphatase leads to abnormal accumulation of glycogen in the liver
d) The reaction occurs in mitochondria
30. Which of the following statement is true about Cori Cycle?
a) The Cori cycle involves three tissues muscle, liver, and brain
b) It involves the transport of lactate from the liver to skeletal tissue for gluconeogenesis
c) It involves the transport of lactate from skeletal muscle to the liver for gluconeogenesis
d) It is active during resting stages and in well-fed condition
31. During prolong starvation, which of the following hormone is responsible for increasing
gluconeogenesis in the liver
a) Insulin
b) Glucagon
c) TSH
d) Thyroxine
32. What is the general term used for the anaerobic degradation of glucose to obtain energy?
A. Anabolism
B. Oxidation
C. Fermentation
D. Metabolism

33. Whenever the cell’s ATP supply is depleted, which of the following enzyme’s activity is increased?
A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1

34. Cleavage of Fructose 1, 6-biophosphate yields ___________

A. Two aldoses
B. Two ketoses
C. An aldose and a ketose
D. Only a ketose

35. Dihydroxyacetone phosphate is rapidly and reversibly converted to ___________

A. Glyceraldehyde 3-phosphate
B. 1, 3-bis-phosphoglycerate
C. Fructose 1, 6-bisphosphate
D. Fructose 6-phosphate

36. What is the first step in the payoff phase of glycolysis?

A. Reduction of 1, 3-bisphosphoglycerate to glyceraldehyde 3-phosphate
B. Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate
C. Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
D. Irreversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate

37. Which substrate is used in the last step of glycolysis?

A. Glyceraldehyde 3-phosphate
B. Pyruvate
C. Phosphoenolpyruvate
D. 1, 3-bisphosphoglycerate

38. High concentration of glucose 6-phosphate is inhibitory to ___________

A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
39. The product formed in the first substrate level phosphorylation in glycolysis is ___________
A. Pyruvate
B. 3-phosphoglycerate
C. 1, 3-bisphosphoglycerate
D. 2-phosphoglycerate

40. Glycolysis converts ___________

A. Glucose into pyruvate
B. Glucose into phosphoenolpyruvate
C. Fructose into pyruvate
D. Fructose into phosphoenolpyruvate

41. The following enzymes catalyze a decarboxylation reaction of pyruvate:

a. Pyruvate kinase
b. Pyruvate dehydrogenase
c. Pyruvate carboxylase
d. Isocitrate dehydrogenase

42. 2. Which of the following statements is known as the rate-limiting step in glycolysis?
a. Enolase
b. Phosphofructokinase
c. Phosphohexose isomerase
d. Glyceraldehyde-3-phosphate dehydrogenase

43. 3. In erythrocytes, the end product of glycolysis is:

a) Pyruvate
b) Acetyl-CoA
c) Lactate
d) 2,3 Bisphosphoglycerate

44. 4. What is the net production of ATP in aerobic glycolysis?

a. 2 ATP
b. 4 ATP
c. 6 ATP
d. 8 ATP

45. 5. The degradative processes are also called as:

a. Catabolism
b. Anabolism
c. Amphibolism
d. Metabolism

46. 6. The biosynthetic reactions involving the formation of complex molecules from simple processes are
nown as:
a. Metabolism
b. Amphibolism
c. Anabolism
d. Catabolism
47. 7. Name the enzyme which is responsible for the conversion of phosphoenolpyruvate (PEP) to pyruvate:
a. Pyruvate carboxylase
b. Pyruvate dehydrogenase
c. Pyruvate kinase
d. Phosphofructokinase
48. 8. Which hormone negatively regulates glucokinase, PFK, and Pyruvate Kinase (PK)?
a. Insulin
b. Glucagon
c. GH
d. Epinephrine
49. 9. pyruvate kinase (PK) is allosterically activated by:
a. Fructose-1,6-Bisphosphate
b. Citrate
c. Acetyl CoA
d. Alanine
50. 10. The conversion of Glucose-6-Phosphate to Fructose-6-Phosphate is an example of:
a. Phosphorylation
b. Isomerization
c. Oxidation
d. Aldol cleavage
51. 11. The end product of Glycolysis under anaerobic conditions is -
a) Lactic acid
b) Pyruvate
c) Acetyl CoA
d) Oxaloacetic acid
52. 12. Sodium-independent facilitated diffusion transport system is mediated by:
a. GLUT-1
b. GLUT-14
c. GLUT-1 to GLUT-14
d. SGLT
53. 13. Sodium–monosaccharide co-transport system transports glucose ______a concentration gradient:
a. against
b. with
54. 14. The first five reactions of glycolysis correspond to an energy __________ phase:
a. generation
b. investment
55. 15. Glucokinase is an enzyme present in the:
a. liver
b. all cells
c. Pancreas
d. muscles
56. 16. PFK-1 is controlled by the available concentrations of the substrates:
a. ATP
b. fructose 6-phosphate
c. fructose 2,6-bisphosphate
d. all of these
57. 17. Major mechanism(s) for oxidizing NADH is (are):
a. conversion of pyruvate to lactate
b. The respiratory chain
c. both a & b
d. None of these
58. 18. The reaction in glycolysis catalyzed by_______ is an example of substrate-level phosphorylation:
a. pyruvate kinase (PK)
b. Pyruvate dehydrogenase
c. Pyruvate carboxylase
d. Lactate dehydrogenase
59. 19. What is the net production of ATP per molecule of glucose in anaerobic glycolysis?
a. 2 ATP
b. 4 ATP
c. 6 ATP
d. 8 ATP
60. 20. Pyruvate dehydrogenase converts pyruvate into_______ which is a major fuel for the TCA cycle.
a. lactate
b. Oxaloacetate
c. ethanol
d. acetyl CoA
61. 21. Reduction of pyruvate to ethanol occurs in:
a. erythrocyte
b. yeast
c. muscles
d. None of these
62. 22. _______reactions require energy, which is generally provided by the hydrolysis of ATP.
a. Anabolic
b. Catabolic
63. 23. The rate of a metabolic pathway can respond to regulatory signals such as:
a. Allosteric activators
b. Allosteric inhibitors
c. Allosteric activators or inhibitors
d. None of these
64. 24. The most important signaling between cells is chemical signaling such as:
a. hormones
b. neurotransmitters
c. both a & b
d. None of these
65. 25. catabolism is a _________ process.
a. convergent
b. divergent
66. 26. Catabolic pathways are typically oxidative, and require:
a. NAD+
b. NADPH