Which cell ingests bacteria and cellular debris?

• A. Lymphocyte
• B. Phagocyte
• C. Erythrocyte
• D. Platelet

Answer: (B)

Phagocytes perform phagocytosis, the process of engulfing and digesting bacteria and cellular debris as a frontline defense. When a pathogen is encountered, the cell stretches its membrane to surround it, forming a phagosome. This phagosome then fuses with a lysosome to create a phagolysosome, where digestive enzymes and reactive molecules break down the invader or debris. Some phagocytes also present digested bits to other immune cells to help coordinate the response. The other options aren’t primarily involved in ingesting microbes: lymphocytes handle targeted immune signaling and responses, erythrocytes carry oxygen, and platelets help with clotting.