It acts as a molecular sieve,controlling the passage of large molecules.

$A$: The main structural component of the membranes of various cellular organelles is protein.
$R$: Protein is an important component of protoplasm.

The membrane of the erythrocytes has approximately . . . . . . $\%$ of proteins and . . . . . . $\%$ lipids.

For the cell membrane, the name "plasmalemma" was given by:

What is the pump in active transport?

The plasma membrane is composed of