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: -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-3: -During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose.

Detailed explanation-4: -During photosynthesis, light energy (sunlight) combines with the reactants-water and carbon dioxide-to form new products: glucose (sugar) and oxygen.

Detailed explanation-5: -How Stomata Work. Each stoma (the tiny pore or hole) is flanked by two guard cells which expand and contract, closing and opening the stoma. Two controls on the opening and closing of the stomata are the plant’s water balance and the carbon dioxide concentration.