AP BIOLOGY

Detailed explanation-1: -The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (the extracellular space).

Detailed explanation-2: -Why it is called a plasma membrane? The cell contains a protoplasm (or simply plasm), which is the semi-fluid living matter. This living matter or plasm is contained inside a biological membrane referred to as the plasma membrane.

Detailed explanation-3: -In eukaryotic cells, which have a nucleus, the cytoplasm is everything between the plasma membrane and the nuclear envelope. In prokaryotes, which lack a nucleus, cytoplasm simply means everything found inside the plasma membrane.