Question

level 5 q1 when oxygen is not present, what process is used to break down pyruvate? a. fermentation b. aerobic respiration c. photosynthesis d. oxidative phosphorylation a. fermentation b. aerobic respiration

Explanation:

To solve this, we analyze each option:

• Option A: Fermentation occurs in the absence of oxygen and breaks down pyruvate (from glycolysis) to produce energy (e.g., lactic acid or alcohol fermentation).
• Option B: Aerobic respiration requires oxygen and uses pyruvate in the citric acid cycle and oxidative phosphorylation, so it's incorrect here.
• Option C: Photosynthesis is the process of converting light energy to chemical energy in plants, algae, etc., and doesn't involve breaking down pyruvate, so it's incorrect.
• Option D: Oxidative phosphorylation is part of aerobic respiration and requires oxygen, so it's incorrect.

So the correct process for breaking down pyruvate without oxygen is fermentation.

Answer:

A. Fermentation