Which statement about phagocytosis is accurate?

• A. It involves engulfing large particles with pseudopods
• B. It uses vesicles to transport small molecules
• C. It relies on endoplasmic reticulum function
• D. It is identical to pinocytosis

Answer: (A)

Phagocytosis is the process by which certain immune cells engulf large particles by extending membrane projections called pseudopods, which surround the target and pinch off to form a phagosome. This mechanism relies on actin-driven cytoskeletal remodeling to cradle big particles like bacteria or debris, followed by fusion of the phagosome with lysosomes for digestion. This distinguishes it from other forms of endocytosis. For example, pinocytosis involves taking in fluids and dissolved solutes through small vesicles, not large particles, so it isn’t the same as phagocytosis. Phagocytosis is not defined by a requirement for the endoplasmic reticulum, and it isn’t identical to pinocytosis.