What is osmosis in the context of cellular biology?

Osmosis is specifically defined as the movement of water molecules through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. This process occurs to achieve equilibrium between the solute concentrations on both sides of the membrane. By moving water toward the area with higher solute concentration, the cell can regulate its internal environment and maintain homeostasis. This process is crucial in cellular biology because it influences cell volume, turgor pressure in plant cells, and overall cellular function.

In contrast, the other choices describe different processes. The movement of proteins through active transport involves energy and is related to the movement of specific molecules rather than water. The diffusion of solutes across a membrane pertains to the movement of solutes without focusing on water, which is not the right definition of osmosis. Lastly, the passive transport of glucose is a separate process that may involve facilitated diffusion through transport proteins, distinctly different from the osmosis process that specifically highlights water movement.