At which stage is glucose broken into smaller molecules?

Question

before cellular respiration begins
during the first stage of cellular respiration
during the second stage of cellular respiration
at the end of cellular respiration

Answer 1

Glucose is broken into smaller molecules during the first stage of cellular respiration, which is called glycolysis. In glycolysis, one molecule of glucose (a six-carbon sugar) is converted into two molecules of pyruvate (a three-carbon compound), along with the production of a small amount of ATP and NADH.