AP BIOLOGY

Detailed explanation-1: -Carbon dioxide and oxygen cannot pass through the cuticle, but move in and out of leaves through openings called stomata (stoma = “hole"). Guard cells control the opening and closing of stomata. When stomata are open to allow gases to cross the leaf surface, the plant loses water vapor to the atmosphere.

Detailed explanation-2: -Gas exchange When a plant is carrying out photosynthesis carbon dioxide needs to move from the air into the leaf. It does this by diffusing through small pores called stomata. At the same time oxygen moves out of the leaf through the stomata. This movement of gases in opposite directions is called gas exchange.

Detailed explanation-3: -When photosynthesis occurs, carbon dioxide diffuses into the leaf through the stomata (pores, or tiny holes, in the leaf) while oxygen moves out of the leaf in the same way. NOTE: stomata is plural, stoma is singular.

Detailed explanation-4: -The only way for gases to diffuse in and out of the leaf is though small openings on the underside of the leaf, the stomata. These stomata can open and close according to the plant’s needs. The tissues of the leaf in between the epidermal cells, into which gases diffuse from the stomata, are called mesophyll.