What is the definition of osmosis?

Osmosis is specifically defined as the movement of water molecules across a semi-permeable membrane. This process occurs when there is a concentration gradient of water across the membrane, meaning that water moves from an area of higher water concentration (or lower solute concentration) to an area of lower water concentration (or higher solute concentration). This movement continues until equilibrium is reached, where the concentration of water is balanced on both sides of the membrane.

The semi-permeable membrane allows for the passage of water molecules while restricting most solutes, which is crucial in biological systems for maintaining cellular homeostasis. Osmosis plays a vital role in processes like nutrient absorption and waste removal in cells, as well as in the regulation of cell volume and internal pressure.

Understanding this definition is essential for comprehending various biological processes, including how cells interact with their environment and maintain their integrity in different solute conditions.