Multiple choice

What happens to glucose during strenuous exercise?

  1. It is converted to glycogen.

  2. It is converted to pyruvic acid .

  3. It is converted to starch.

  4. It is converted to lactic acid.

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During strenuous exercise, when oxygen supply cannot meet the demand, muscle cells undergo anaerobic respiration. Pyruvate from glycolysis is converted to lactic acid (lactate) instead of entering the Krebs cycle. This allows glycolysis to continue by regenerating NAD+. Glycogen is broken down to glucose (not vice versa), and starch is not involved in animal metabolism.