How does osmosis differ from diffusion?

Osmosis is the movement of water across a semi-permanent membrane, while diffusion involves the movement of particles from high to low concentration.

Osmosis and diffusion are both passive transport processes, which means they do not require energy to occur. However, they differ in the types of substances they transport and the conditions required for the process to occur. Osmosis specifically refers to the movement of water molecules across a semi-permeable membrane. This movement is from an area of lower solute concentration to an area of higher solute concentration. The semi-permeable membrane allows water molecules to pass through, but not the solute particles, leading to a net movement of water to the side with higher solute concentration.

On the other hand, diffusion is a more general process that involves the movement of particles from an area of high concentration to an area of low concentration. This can involve any type of particles, such as gases, liquids, or dissolved solids, and does not require a semi-permeable membrane. The particles move randomly and spread out until they are evenly distributed, achieving a state of equilibrium.

In terms of their roles in biological systems, both osmosis and diffusion are crucial for the transport of substances. Osmosis is particularly important in maintaining the water balance in cells and allowing the transport of water-soluble substances. Diffusion, meanwhile, is essential for processes such as gas exchange in the lungs, where oxygen and carbon dioxide diffuse across the thin walls of the alveoli.

In summary, while osmosis and diffusion are similar in that they are both passive transport processes, they differ in the substances they transport and the conditions required for the process. Osmosis is specific to the movement of water across a semi-permeable membrane, while diffusion involves the movement of any particles from an area of high concentration to low concentration.