What is the name given to the process when a cell engulfs solid particles?

The correct term for the process when a cell engulfs solid particles is phagocytosis. This process is a type of endocytosis, where the cell membrane surrounds the solid particles, forming a pocket that eventually pinches off to form a vesicle inside the cell. Phagocytosis is essential for immune responses, as it allows cells such as macrophages to ingest and destroy pathogens and debris.

In contrast, pinocytosis refers to the ingestion of liquid particles, not solids, hence it is tailored for taking in fluids. Exocytosis involves the expulsion of materials from a cell, effectively the opposite of endocytosis. Diffusion is a passive transport mechanism where molecules move from an area of higher concentration to an area of lower concentration without the need for cellular energy or membrane engulfment. Understanding the distinctions between these processes clarifies why phagocytosis is specifically associated with the uptake of solid particles.