Which term describes the engulfing of material by a cell?

Which term describes the engulfing of material by a cell?

• A. Exocytosis
• B. Endocytosis
• C. Diffusion
• D. Osmosis

Answer: (B)

Endocytosis is the process described. In endocytosis, the cell membrane folds inward and surrounds external material, pinching off to form a vesicle that brings the substance into the cell. This can occur with solid particles (phagocytosis) or with liquids and small molecules (pinocytosis). Endocytosis is essential for nutrient uptake and immune defense, such as immune cells engulfing pathogens. The opposite process is exocytosis, where vesicles inside the cell fuse with the membrane to release contents outside the cell. Diffusion simply moves particles down their concentration gradient without vesicle formation, and osmosis is the diffusion of water across a selectively permeable membrane.

Endocytosis is the process described. In endocytosis, the cell membrane folds inward and surrounds external material, pinching off to form a vesicle that brings the substance into the cell. This can occur with solid particles (phagocytosis) or with liquids and small molecules (pinocytosis). Endocytosis is essential for nutrient uptake and immune defense, such as immune cells engulfing pathogens. The opposite process is exocytosis, where vesicles inside the cell fuse with the membrane to release contents outside the cell. Diffusion simply moves particles down their concentration gradient without vesicle formation, and osmosis is the diffusion of water across a selectively permeable membrane.