Osmosis:
Osmosis is the process by which molecules of a solvent (usually water) move from an area of low solute concentration to an area of high solute concentration through a semipermeable membrane. This movement occurs in order to equalize the concentration of solute on both sides of the membrane.
- Definition: Osmosis is the passive movement of water molecules across a semipermeable membrane.
- Mechanism: Water moves through the membrane to dilute the side with higher solute concentration.
- Importance: Osmosis is crucial for maintaining the balance of fluids in living organisms.
- Examples: Osmosis is responsible for the absorption of water in plant roots and the rehydration of cells in our body.

Diffusion:
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration, without the need for a membrane. This movement occurs due to the random motion of molecules and leads to the equal distribution of particles in a given space.
- Definition: Diffusion is the passive movement of molecules from an area of high concentration to low concentration.
- Mechanism: Molecules move randomly and spread out to achieve equilibrium.
- Importance: Diffusion is essential for various biological processes such as gas exchange in the lungs and nutrient absorption in the intestines.
- Examples: Oxygen and carbon dioxide diffuse across the alveoli in the lungs during respiration, while nutrients diffuse across the intestinal lining for absorption.
In summary, osmosis and diffusion are fundamental processes in biology that help maintain equilibrium and facilitate the movement of molecules in living organisms. Understanding these mechanisms is crucial for comprehending various physiological processes and their significance in biological systems.