- The net movement of particles of a gas or a solute from an area of high concentration to a low concentration (along the concentration gradient).
- The greater the concentration gradient, the faster the rate of diffusion
- Oxygen diffuses into cells for respiration
- The net movement of water from a high to low water potential along a concentration gradient.
- The different concentrations of free water outside causes the water to enter or leave the cell.
- Isotonic: the same water potential on both sides of the membrane
- Hypotonic: more water in the cell than outside