Which gas produced in photosynthesis is released by leaves and used by other organisms?

• A. Carbon dioxide
• B. Nitrogen
• C. Hydrogen
• D. Oxygen

Answer: (D)

During photosynthesis, plants capture light energy to convert carbon dioxide and water into glucose, and a byproduct of this process is oxygen gas that is released from the leaves. In the light-dependent reactions, water is split to supply electrons, and the leftover oxygen atoms join to form O2, which exits the leaf through the stomata and becomes available in the atmosphere for other organisms to use in respiration. While carbon dioxide is taken up for making glucose, nitrogen and hydrogen aren’t released as a gas by this process. The oxygen released by leaves is what other organisms rely on to obtain energy from their own food.