Question

Total how many ATP molecules are formed by substrate-level phosphorylation in glycolysis?

• A. 8 ATP
• B. 4 ATP
• C. 36 ATP
• D. 2 ATP

Hint:

In glycolysis, 4 ATP molecules are produced by substrate-level phosphorylation, but 2 ATP molecules are consumed, resulting in a net gain of 2 ATP.

Answer 1

The Correct Option is B

Step 1: Understanding substrate-level phosphorylation.
Substrate-level phosphorylation occurs in glycolysis, where ATP is synthesized by transferring a phosphate group from a substrate to ADP. In glycolysis, 4 ATP molecules are produced via this process. However, 2 ATP molecules are consumed in the initial steps, resulting in a net gain of 2 ATP.
Step 2: Analyzing the options.
(A) 8 ATP: Incorrect — A total of 8 ATP is not generated by substrate-level phosphorylation in glycolysis.
(B) 4 ATP: Correct — 4 ATP molecules are produced during glycolysis, but 2 ATP are used, resulting in a net gain of 2 ATP.
(C) 36 ATP: Incorrect — 36 ATP molecules are not produced in glycolysis; this total is closer to the ATP produced in cellular respiration.
(D) 2 ATP: Incorrect — This is the net ATP produced, not the total produced by substrate-level phosphorylation.
Step 3: Conclusion.
The correct answer is (B) 4 ATP, as 4 ATP are produced via substrate-level phosphorylation during glycolysis.