Why are photosynthesis and respiration considered opposite reactions?

Answer 1

The process of photosynthesis stores energy in the form of chemical bonds (in carbohydrates including glucose, or sugar) and in the process releases free oxygen by breaking down carbon dioxide. Cellular respiration absorbs free oxygen, to release energy stored in the chemical bonds of food. This oxidation creates carbon dioxide, completing the cycle of carbon through the biosystem.

(Some forms of respiration are anaerobic, not using oxygen, and break down carbohydrates in a different manner, releasing either carbon dioxide or methane. The net result is the same: removing energy from the carbohydrate bonds.)

Answer 2

Photosynthesis and cellular respiration are said to be reverse chemical processes because the reactants of photosynthesis are the products of cell respiration and the reactants of cell respiration are the products of photosynthesis.

Answer 3

Hi there!
Aerobic respiration is the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen.
Protein synthesis is one of the many uses of releasing energy in the human body.