HESI A2 Biology 2025 – 400 Free Practice Questions to Pass the Exam

Osmosis is the process that describes the movement of water through a semipermeable membrane. In osmosis, water molecules move from an area of lower solute concentration to an area of higher solute concentration. This movement continues until equilibrium is reached, where the concentration of solute is balanced on both sides of the membrane.

In biological systems, semipermeable membranes allow water to pass through while restricting the movement of solute particles. This selective permeability is crucial for maintaining cell homeostasis and regulating the internal environment of cells. For example, in a plant cell, osmosis helps to maintain turgor pressure, which keeps the cell rigid and supports the plant's structure.

The other processes listed do not specifically refer to the movement of water through a semipermeable membrane. Diffusion typically involves the movement of solutes and does not specifically involve water. Active transport requires energy to move substances against their concentration gradient and does not apply to passive movement processes like osmosis. Endocytosis refers to the process by which cells engulf material from their environment, which does not pertain to the passive movement of water through membranes.