Why is anaerobic respiration in human skeletal muscle during strenuous exercise characterized by the accumulation of lactic acid?
Answer and explanation
Correct answer: B. pyruvate is reduced to lactate to regenerate NAD+ for continued glycolysis
- Step 1: In the absence of sufficient oxygen, the electron transport chain halts. Step 2. To allow glycolysis to continue producing 2 ATP per glucose, NADH must transfer electrons to pyruvate. Step 3. Lactate dehydrogenase reduces pyruvate to lactic acid, regenerating NAD⁺. Answer: pyruvate is reduced to lactate to regenerate NAD+ for continued glycolysis. Why not the others: Ethanol fermentation occurs in yeast, not human muscles; oxygen is depleted, not in excess; uric acid is a purine excretory product.
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