Which molecule is produced during photosynthesis that is used in cellular respiration?

• A. Oxygen
• B. Carbon dioxide
• C. Water
• D. Glucose

Answer: (D)

Photosynthesis stores energy in chemical bonds, and the main molecule it makes that serves as fuel for cellular respiration is glucose. In photosynthesis, plants build glucose from carbon dioxide and water using light energy. In cellular respiration, cells break down that glucose to release energy and make ATP, with oxygen used and carbon dioxide and water produced as byproducts. So glucose is the molecule produced by photosynthesis that organisms use to power respiration. Oxygen is indeed involved in respiration and is produced by photosynthesis, but it isn’t the energy-carrying molecule produced by photosynthesis that fuels respiration.