Osmosis and Diffusion

• Water Potential - a measure of the tendancy of water molecules to diffuse from one place to another.
• Solvent - a liquid that dissolves a solvent e.g. Water.
• Solute - the thing that is to be dissolved e.g. salt.
• Solution - the solute and the solvent mixed together.
• Passive process - Does not require energy for the process to take place
• Haemolysis - when an animal cell bursts because too much water has been taken into the cell. the cell becomes haemolysed.
• Turgid - when a plant cell is turgid, the cell membrane pushes against the cell wall. the cell wall prevents bursting when a lot of water is taken in unlike in an animal cell.
• Crenation - this is when a lot of water leaves an animal cell, and it becomes wrinkled.
• Plasmolysis - when the cell membrane pulls away from the cell wall because a lot of water leaves the cell (plant cells only). The cell becomes plasmolysed.

Osmosis is a form of diffusion, so it is a passive process (requires no energy). It is a measure of the net movement of water from a region with high water potential (or a high concentration of water molecules) to a region with low water potential across a partially permeable membrane.