Biochemistry Multiple Choice Questions on “Glycolysis”.
1. Which of the following enzyme catalyzes the first step of glycolysis?
A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
Answer: A
Clarification: The first of glycolysis is irreversible under intracellular conditions and is catalyzed by hexokinase.
2. What is the general term used for the anaerobic degradation of glucose to obtain energy?
A. Anabolism
B. Oxidation
C. Fermentation
D. Metabolism
Answer: C
Clarification: Fermentation is the general term used for the degradation of glucose to obtain energy in the form of ATP.
3. 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
Answer: D
Clarification: Phosphofructokinase-1 is a regulatory enzyme; it is the major point of regulation in glycolysis. Its activity is increased whenever the cell’s ATP supply is depleted.
4. Cleavage of Fructose 1, 6-biophosphate yields ___________
A. Two aldoses
B. Two ketoses
C. An aldose and a ketose
D. Only a ketose
Answer: C
Clarification: Fructose 1, 6-biophosphate is cleaved to yield glyceraldehyde 3-phosphate, an aldehyde and dihydroxyacetone phosphate, a ketose.
5. 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
Answer: A
Clarification: Dihydroxyacetone phosphate is rapidly and reversibly converted to glyceraldehyde 3-phosphate by triose phosphate isomerase.
6. 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
Answer: B
Clarification: Glyceraldehyde 3-phosphate dehydrogenase catalyzes the first step in the payoff phase, oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate.
7. Which substrate is used in the last step of glycolysis?
A. Glyceraldehyde 3-phosphate
B. Pyruvate
C. Phosphoenolpyruvate
D. 1, 3-bisphosphoglycerate
Answer: C
Clarification: The last step in glycolysis is the transfer of phosphoryl group from phosphoenolpyruvate to ADP catalyzed by pyruvate kinase.
8. High concentration of glucose 6-phosphate is inhibitory to ___________
A. Hexokinase
B. Pyruvate kinase
C. Glucokinase
D. Phosphofructokinase-1
Answer: A
Clarification: Hexokinase catalyzes the reaction involving conversion of glucose to glucose 6-phosphate.
9. The product formed in the first substrate level phosphorylation in glycolysis is ___________
A. Pyruvate
B. 3-phosphoglycerate
C. 1, 3-bisphosphoglycerate
D. 2-phosphoglycerate
Answer: B
Clarification: Phosphoglycerate kinase transfers phosphoryl group from 1, 3-bisphosphoglycerate to ADP forming ATP and 3-phosphoglycerate.
10. Glycolysis converts ___________
A. Glucose into pyruvate
B. Glucose into phosphoenolpyruvate
C. Fructose into pyruvate
D. Fructose into phosphoenolpyruvate
Answer: A
Clarification: Glycolysis is a metabolic pathway that converts glucose into pyruvate.
.