What process is described as cell eating?

The correct answer is phagocytosis, often referred to as "cell eating." This process involves the engulfing of larger particles, such as bacteria, dead cells, or other debris, by a cell. In phagocytosis, the cell membrane extends outward to form projections called pseudopodia, which surround and enclose the particle. Once the particle is enclosed, it forms a vesicle within the cell, allowing for digestion and processing of the material by lysosomal enzymes.

Phagocytosis is an essential function of certain immune cells, such as macrophages and neutrophils, which help protect the body by removing pathogens and dead or damaged cells. This process is vital for maintaining tissue homeostasis and for the adaptive immune response.

Other processes mentioned have different functions. Exocytosis, for example, involves the expulsion of materials from a cell, while pinocytosis is a form of endocytosis that entails the ingestion of fluid and solutes, often referred to as "cell drinking." Diffusion, on the other hand, is the passive movement of particles from an area of higher concentration to one of lower concentration and does not involve the active cellular uptake of particles. Understanding these distinctions is crucial in cell biology and immunology.