GENERAL HISTOLOGY

Detailed explanation-1: -The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment. The cell membrane consists of a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials entering and exiting the cell.

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: -Cholesterol, a major component of animal plasma membranes, regulates the fluidity of the overall membrane, meaning that cholesterol controls the amount of movement of the various cell membrane components based on its concentrations.