Which process is a form of active transport in which substances enter the cell by engulfment?

Which process is a form of active transport in which substances enter the cell by engulfment?

• A. Endocytosis
• B. Exocytosis
• C. Facilitated diffusion
• D. Osmosis

Answer: (A)

Engulfment of external material by the cell membrane to form a vesicle is endocytosis, an active transport process because it requires cellular energy to reshape the membrane and pull substances inside. In endocytosis, the membrane wraps around the material, creating a vesicle that carries the cargo into the cytoplasm. This contrasts with exocytosis, which releases contents from the cell, and with facilitated diffusion and osmosis, which move substances passively down their gradients without energy input. Endocytosis includes phagocytosis for solid particles, pinocytosis for liquids, and receptor‑mediated endocytosis for specific molecules. So the described process of engulfment corresponds to endocytosis.

Engulfment of external material by the cell membrane to form a vesicle is endocytosis, an active transport process because it requires cellular energy to reshape the membrane and pull substances inside. In endocytosis, the membrane wraps around the material, creating a vesicle that carries the cargo into the cytoplasm. This contrasts with exocytosis, which releases contents from the cell, and with facilitated diffusion and osmosis, which move substances passively down their gradients without energy input. Endocytosis includes phagocytosis for solid particles, pinocytosis for liquids, and receptor‑mediated endocytosis for specific molecules. So the described process of engulfment corresponds to endocytosis.