AP BIOLOGY

Detailed explanation-1: -Through photosynthesis, they use sunlight and carbon dioxide to make food, belching out the oxygen that we breathe as a byproduct. This evolutionary innovation is so central to plant identity that nearly all land plants use the same pores-called stomata-to take in carbon dioxide and release oxygen.

Detailed explanation-2: -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-3: -When stomata are open, water vapor and other gases, such as oxygen, are released into the atmosphere through them. A number of factors can affect the exchange of gases between a leaf and the atmosphere.

Detailed explanation-4: -Carbon dioxide (CO₂), oxygen (O₂) and water (H₂0) commonly move in or out via the stomata. While gas exchange occurs, carbon (C) stays inside the leaf as a building block for the plant. Often, stomata are open during the day when photosynthesis is taking place and closed at night when it stops.