What is the term for the process by which cells take in substances?

The process by which cells take in substances is known as endocytosis. This mechanism involves the cell membrane folding inward to enclose a substance, forming a vesicle that brings the material into the cell. Endocytosis is crucial for the uptake of larger molecules and particles that cannot simply pass through the cell membrane.

In contrast, exocytosis refers to the process in which cells expel substances, moving materials out of the cell rather than bringing them in. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration, which occurs without the need for the cell to actively take in substances. Osmosis specifically deals with the movement of water molecules through a semipermeable membrane, and while it is a form of diffusion, it is distinct from the process of taking in solid substances. Each of these processes plays a unique role in cell function, but endocytosis directly addresses the question of how cells intake materials.