In leaf physiology, which process is a function of leaves in addition to photosynthesis and transpiration?

• A. Transpiration
• B. Respiration
• C. Photosynthesis
• D. Absorption

Answer: (B)

Leaves also perform respiration. Respiration is the cellular process that breaks down sugars produced by photosynthesis to release energy (ATP) needed for maintenance, growth, and active transport. This happens in leaf cell mitochondria continuously, day and night, using oxygen and releasing carbon dioxide and water. While photosynthesis captures light energy to build sugars and transpiration regulates water loss and gas exchange, respiration provides the energy that powers the leaf’s ongoing cellular activities. Absorption isn’t a typical leaf function in trees, since uptake of water and minerals mostly occurs through the roots.