biology : class11 Second Substrate-Level Phosphorylation : Location, Steps, Products, ATP Yield : Glycolysis MCQ Questions and Answers
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Second Substrate-Level Phosphorylation
MCQ questions and answers.
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MCQ Questions
1. Which enzyme catalyzes the second substrate-level phosphorylation in glycolysis?
A.
Hexokinase
B.
Phosphofructokinase
C.
Pyruvate kinase
D.
Phosphoglycerate kinase
Correct Answer:
Pyruvate kinase
Explanation:
Pyruvate kinase catalyzes the transfer of a phosphate group from phosphoenolpyruvate to ADP, forming ATP and pyruvate.
2. Which molecule donates the phosphate group during the second substrate-level phosphorylation of glycolysis?
A.
Glucose
B.
Phosphoenolpyruvate
C.
Fructose-6-phosphate
D.
Glyceraldehyde-3-phosphate
Correct Answer:
Phosphoenolpyruvate
Explanation:
Phosphoenolpyruvate, or PEP, donates its phosphate group to ADP during the second substrate-level phosphorylation.
3. Which molecule receives the phosphate group in the second substrate-level phosphorylation of glycolysis?
A.
ATP
B.
NAD+
C.
ADP
D.
Pyruvate
Correct Answer:
ADP
Explanation:
ADP receives the phosphate group from phosphoenolpyruvate and is converted into ATP.
4. What is the main product formed from phosphoenolpyruvate during the second substrate-level phosphorylation?
A.
Glucose
B.
Pyruvate
C.
Lactate
D.
Acetyl-CoA
Correct Answer:
Pyruvate
Explanation:
When phosphoenolpyruvate donates its phosphate group, it is converted into pyruvate.
5. How many ATP molecules are formed by the second substrate-level phosphorylation from one glucose molecule?
A.
One ATP molecule
B.
Two ATP molecules
C.
Three ATP molecules
D.
Four ATP molecules
Correct Answer:
Two ATP molecules
Explanation:
One glucose molecule produces two phosphoenolpyruvate molecules, and each forms one ATP in the second substrate-level phosphorylation.
6. The second substrate-level phosphorylation occurs during which conversion in glycolysis?
A.
Glucose to glucose-6-phosphate
B.
Fructose-6-phosphate to fructose-1,6-bisphosphate
C.
1,3-bisphosphoglycerate to 3-phosphoglycerate
D.
Phosphoenolpyruvate to pyruvate
Correct Answer:
Phosphoenolpyruvate to pyruvate
Explanation:
The second substrate-level phosphorylation is the conversion of phosphoenolpyruvate into pyruvate, accompanied by ATP formation.
7. Which type of reaction occurs in the second substrate-level phosphorylation of glycolysis?
A.
Direct transfer of a phosphate group to ADP
B.
Transfer of electrons to oxygen
C.
Removal of carbon dioxide from glucose
D.
Formation of NADH from NAD+
Correct Answer:
Direct transfer of a phosphate group to ADP
Explanation:
In substrate-level phosphorylation, a phosphate group is directly transferred from a phosphorylated substrate to ADP, forming ATP.
8. At which stage of glycolysis does the second substrate-level phosphorylation take place?
A.
First step
B.
Third step
C.
Seventh step
D.
Tenth step
Correct Answer:
Tenth step
Explanation:
The second substrate-level phosphorylation occurs in the tenth and final step of glycolysis, catalyzed by pyruvate kinase.
9. What is produced along with ATP when phosphoenolpyruvate undergoes the second substrate-level phosphorylation?
A.
Pyruvate
B.
Glucose
C.
NADH
D.
Fructose-1,6-bisphosphate
Correct Answer:
Pyruvate
Explanation:
The reaction catalyzed by pyruvate kinase produces both ATP and pyruvate from phosphoenolpyruvate and ADP.
10. Why is the second substrate-level phosphorylation important in glycolysis?
A.
It produces ATP directly without an electron transport chain
B.
It converts ATP into glucose
C.
It produces oxygen for glycolysis
D.
It breaks pyruvate into carbon dioxide
Correct Answer:
It produces ATP directly without an electron transport chain
Explanation:
The second substrate-level phosphorylation generates ATP by direct phosphate transfer from phosphoenolpyruvate to ADP, without using the electron transport chain.
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