<unk>   is a process where cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane. It is used by all cells of the body because most substances important to them are large polar molecules, and thus cannot pass through the hydrophobic plasma membrane. The function of<unk>  is the opposite of exocytosis.
Endocytosis
Excretion
Chemotaxis
Secretion
Resorption
Adsorption
Extraction 
Drug metabolism