What is the primary purpose of stomata on leaves?

• A. To regulate water loss
• B. To regulate gas exchange and water loss
• C. To absorb nutrients
• D. To store sugars

Answer: (B)

Stomata are openings on the leaf surface that are controlled by guard cells to balance gas exchange with water loss. They open to let carbon dioxide diffuse into the leaf for photosynthesis and release oxygen, while also allowing water vapor to escape through transpiration. This dual role is essential: enough CO2 must enter for the plant to photosynthesize, but opening too much leads to excessive water loss. Thus, their primary purpose is to regulate both gas exchange and water loss, enabling photosynthesis while managing water use. Nutrient absorption and sugar storage aren’t functions of stomata.