Osmosis is the passive movement of water molecules across a selectively permeable membrane from a region of lower solute concentration (higher water concentration) to a region of higher solute concentration (lower water concentration).

The driving force for osmosis is the difference in water concentration across the membrane. Water moves down its concentration gradient, from an area where there are more water molecules to an area where there are fewer water molecules.

Osmosis plays a vital role in many biological processes, such as the absorption of water by plants, the excretion of waste products by kidneys, and the regulation of fluid balance in cells.

Osmotic Pressure

When a semipermeable membrane separates two solutions with different solute concentrations, the pressure that must be applied to the more concentrated solution to prevent the movement of water across the membrane is called the osmotic pressure.

Osmotic pressure is a measure of the tendency of water to move across a semipermeable membrane. The greater the difference in solute concentration between the two solutions, the greater the osmotic pressure.

Osmotic pressure is an important concept in biology and chemistry. It is used to understand a variety of biological processes, such as the movement of water into and out of cells and the function of kidneys.