What is phagocytosis?

• A. White blood cells engulfing and breaking down pathogens using digestive enzymes
• B. Antibodies neutralise toxins
• C. T cells produce memory cells
• D. Bacteria engulf pathogens

Answer: (A)

Phagocytosis is the process by which certain white blood cells, like neutrophils and macrophages, ingest and destroy invading pathogens. They recognize and surround the invader, form a vesicle called a phagosome, which then fuses with a lysosome to create a phagolysosome where digestive enzymes break down the pathogen. This is a fast, non-specific defense of the innate immune system, and it helps by removing microbes and can also expose pieces of the pathogen to activate the adaptive immune response. The description “white blood cells engulfing and breaking down pathogens using digestive enzymes” matches this mechanism exactly. Antibodies neutralize toxins, T cells producing memory cells, and bacteria engulfing pathogens refer to other immune processes or scenarios and do not describe phagocytosis.