EVERYDAY SCIENCE

Detailed explanation-1: -Plants have a waxy cuticle on their leaves to prevent desiccation, or drying out. 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.

Detailed explanation-2: -During respiration, which occurs in most plants at night, plants take in oxygen through the closed stoma and release carbon dioxide into the environment. Both carbon dioxide and oxygen enter and exit through the stoma by simple diffusion down their concentration gradients.

Detailed explanation-3: -The exchange of oxygen and carbon dioxide in the leaf (as well as the loss of water vapor in transpiration) occurs through pores called stomata (singular = stoma). Normally stomata open when the light strikes the leaf in the morning and close during the night.

Detailed explanation-4: -A stoma is a pore, found in the leaf and stem epidermis that is used for gas exchange. The pore is bordered by a pair of specialised parenchyma cells known as guard cells which are responsible for regulating the size of the opening. The inner wall of the guard cells is thicker than the outer wall.