AP BIOLOGY

Detailed explanation-1: -Plasma membrane is said to be a selectively permeable membrane as it allows some substances to enter the cell, while prevents other substances.

Detailed explanation-2: -The cell membrane is selectively permeable. This means that it only allows the entrance/exit of certain molecules. It doesn’t allow everything. Only the substances that are required go in, and the ones that are waste products (or no longer needed) are removed from the cell.

Detailed explanation-3: -Cell membranes are an example of semi-permeable membranes. Cell membranes allow small molecules such as oxygen, water carbon dioxide, and oxygen to pass through but do not allow larger molecules like glucose, sucrose, proteins, and starch to enter the cell directly.

Detailed explanation-4: -The ‘cell membrane’ (also known as the plasma membrane or cytoplasmic membrane) is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells.

Detailed explanation-5: -The simplest mechanism by which molecules can cross the plasma membrane is passive diffusion. During passive diffusion, a molecule simply dissolves in the phospholipid bilayer, diffuses across it, and then dissolves in the aqueous solution at the other side of the membrane.