Question

which end product of fermentation causes the burning feeling in muscles that are working hard?
o carbon dioxide
o pyruvate
o alcohol
o lactic acid

Explanation:

During strenuous exercise, when oxygen is limited, muscle cells undergo lactic - acid fermentation. The accumulation of lactic acid in muscles causes the burning feeling. Alcohol is a product of alcoholic fermentation in yeast, not in muscle cells. Pyruvate is an intermediate in cellular respiration and fermentation, not the cause of the burning feeling. Carbon dioxide is a by - product of aerobic respiration and some fermentation processes but doesn't cause the muscle burning.

Answer:

A. lactic acid