AP BIOLOGY

Detailed explanation-1: -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-2: -Assertion :Normally stomata are open in the day time and close during the night. Reason: The cause of the opening or closing of stomata is the change in the turgidity of the guard cells.

Detailed explanation-3: -In most plants stomata are closed at night (when photosynthesis cannot operate) and open during the day and the signals to open and close come from environmental cues and an internal circadian clock.

Detailed explanation-4: -Stomata in xerophytes open at night and close during the day as a water-saving adaptation.