Metabolic water is produced during which process?

• A. Photosynthesis.
• B. Cellular respiration.
• C. Glycolysis only.
• D. Digestion of fats.

Answer: (B)

Metabolic water is produced during aerobic energy production in the mitochondria, specifically in oxidative phosphorylation. As electrons move through the electron transport chain, molecular oxygen serves as the final electron acceptor and combines with electrons and hydrogen ions to form water. This water is a byproduct of metabolizing nutrients like glucose and fats and contributes to the body's total water supply.

Photosynthesis uses water to generate oxygen and sugars, so it doesn’t produce metabolic water. Glycolysis occurs earlier in metabolism and yields ATP and NADH but does not generate net water. Digestion of fats involves breaking down molecules rather than producing the water formed in cellular respiration. Thus, the main source of metabolic water is cellular respiration.