What is the process by which cells take in substances via vesicles called?

The process by which cells take in substances via vesicles is known as endocytosis. This mechanism involves the invagination of the cell membrane to form a vesicle that encapsulates extracellular material, allowing it to be internalized into the cell. Endocytosis plays a crucial role in various cellular functions, including nutrient uptake, regulation of membrane composition, and defense against pathogens.

In contrast, exocytosis refers to the process where substances are expelled from the cell through vesicles that fuse with the cell membrane, releasing their contents outside. Diffusion is the passive movement of molecules from an area of higher concentration to one of lower concentration, not involving vesicles. Osmosis specifically refers to the movement of water across a semipermeable membrane, also independent of vesicle formation. Understanding these differences highlights the unique function of endocytosis in cellular systems.