Biology · Bioenergetics

Pyruvic acid is the end product of glycolysis, the first stage of cellular respiration. During glycolysis, one glucose molecule is enzymatically converted into two molecules of pyruvic acid in the cytoplasm, with a net gain of ATP and NADH. Glycolysis does not involve oxygen and precedes the Krebs cycle and electron transport chain, which occur in the mitochondria. The Krebs cycle processes acetyl-CoA, not pyruvic acid, and the electron transport system produces ATP and water. Oxidation is a broader term referring to electron loss and is not specific to producing pyruvic acid.

Correct. Glycolysis is the initial step in cellular respiration, where one glucose molecule is broken down into two molecules of pyruvic acid in the cytoplasm.

Incorrect. The Krebs cycle does not produce pyruvic acid as an end product. Instead, it processes acetyl-CoA to produce ATP, NADH, and FADH2, with oxaloacetic acid being regenerated.

Incorrect. Oxidation is a general chemical process involving the loss of electrons. It is not a specific stage in cellular respiration that ends with pyruvic acid.

Incorrect. The electron transport system, the final stage of cellular respiration, results in the production of water and ATP, not pyruvic acid.