Final answer:
The rates of photosynthesis and respiration in a plant are controlled by the temperature in the leaf, specifically in the mesophyll layer. This exchange of gases occurs through stomata, which are regulated by guard cells.
Step-by-step explanation:
The rates of photosynthesis and respiration in a plant are controlled by the temperature in the leaf. In plants, photosynthesis generally takes place in leaves, specifically in a middle layer called the mesophyll. The exchange of gases like carbon dioxide and oxygen occurs through small, regulated openings called stomata, which are typically located on the underside of the leaf and are regulated by guard cells.