Diffusion:
- Definition: Diffusion is the movement of molecules or particles from an area of higher concentration to an area of lower concentration. It occurs due to the random motion of molecules and does not require any external energy input.
- Substance: Diffusion involves the movement of individual molecules, such as solutes (like salt or sugar molecules) dissolved in a solvent (like water).
- Membrane: The selectively permeable membrane does not significantly hinder the movement of the diffusing molecules.
Osmosis:
- Definition: Osmosis is a specific type of diffusion that involves the movement of water molecules across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.
- Substance: In osmosis, only water molecules move across the membrane, while solutes cannot pass through freely.
- Membrane: The selectively permeable membrane allows water molecules to pass through while blocking the passage of most solutes.
The key distinction between diffusion and osmosis lies in the substances being transported: diffusion applies to any molecule or particle moving down its concentration gradient, whereas osmosis specifically refers to the movement of water molecules across a membrane.
In summary, diffusion is the movement of molecules from high concentration to low concentration, involving solutes or particles and not hindered by the membrane. On the other hand, osmosis is the movement of water molecules from high water concentration to low water concentration through a selectively permeable membrane.
