Question

During vigorous physical exercise, lactic acid is formed

from glucose inside the muscle cells because
(a) there is lack of oxygen (b) there is lack of water

(c) there is excess of carbon dioxide (d) none of the above.​

Answer 1

Anaerobic respiration is the breakdown of glucose in the absence of oxygen. In humans, oxygen-starved muscle cells will respire anaerobically under stress such as heavy physical activity. The by-product of anaerobic respiration in muscles is the lactic acid which causes the puffed out feeling. There is a build-up of lactic acid in the muscles during vigorous exercise. The lactic acid needs to be oxidised to carbon dioxide and water later.

So, the correct answer is 'Lactic acid'.