Use the following information to answer the question below.

The citric acid cycle.
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?
A) Oxaloacetate will decrease and citric acid will accumulate.
B) Oxaloacetate will accumulate and citric acid will decrease.
C) Both oxaloacetate and citric acid will decrease.
D) Both oxaloacetate and citric acid will accumulate.

Question

Use the following information to answer the question below.

The citric acid cycle.
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?
A) Oxaloacetate will decrease and citric acid will accumulate. 
B) Oxaloacetate will accumulate and citric acid will decrease. 
C) Both oxaloacetate and citric acid will decrease. 
D) Both oxaloacetate and citric acid will accumulate.

Quizplus · Accepted Answer

Pyruvate oxidation is the step that generates acetyl-CoA, which enters the citric acid cycle. If pyruvate oxidation is blocked, no acetyl-CoA will be produced, resulting in a buildup of oxaloacetate (which cannot be depleted by the cycle) and a decrease in the levels of citric acid (since acetyl-CoA is required for its production). Therefore, option B is correct.

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