AP BIOLOGY

Detailed explanation-1: -Photosynthesis does not occur in the absence of light during the night. However, respiration occurs in night, necessitating the diffusion of gases. Stomata are not entirely closed at night, thus there is still some room for oxygen and carbon dioxide diffusion.

Detailed explanation-2: -Stomata are mouth-like cellular complexes at the epidermis that regulate gas transfer between plants and atmosphere. In leaves, they typically open during the day to favor CO2 diffusion when light is available for photosynthesis, and close at night to limit transpiration and save water.

Detailed explanation-3: -CAM plants undergo photosynthesis. Therefore, the stomata of such plants only open at night and remain closed throughout the day in order to prevent excessive water loss through transpiration.

Detailed explanation-4: -In succulent plants like Cacti and Bryophyllum, the stomata remain open during night and closed during the day to reduce transpiration. This kind of stomatal behavior is termed scotoactive.

Detailed explanation-5: -Note: In succulent plants stomata close at night and open in day time because there is no sunlight at night for photosynthesis. CAM plants change carbon dioxide into malic acid during night. They do so to avoid the loss of water as they are exposed under high temperature.