What is the process called when the cell membrane engulfs liquid particles?

The correct answer is based on the specific process of cell membrane function. The term "pinocytosis" refers to the process by which cells engulf liquid particles. This is a form of endocytosis, which is a broader category of processes that includes the uptake of both liquids and solids. In pinocytosis, the cell membrane forms small vesicles to internalize extracellular fluid along with any dissolved substances therein.

This process is crucial for nutrient absorption and cellular hydration, allowing cells to take in essential nutrients dissolved in liquid. The distinction between pinocytosis and phagocytosis, for example, lies primarily in the type of materials being engulfed; phagocytosis involves taking in solid particles rather than liquid.

Endocytosis, while also part of this discussion, does not specify the type of particles being engulfed and encompasses various forms including both pinocytosis and phagocytosis.

Understanding these definitions and processes helps clarify the mechanisms by which cells interact with their environment and maintain their physiological functions.