GCSE Biology: Diffusion, Osmosis and Active Transport Worksheet ... - Free Printable

- Definition: Diffusion is the net movement of a substance, from an area of high concentration, to an area of low concentration, across a partially permeable membrane.
- Key Points: Diffusion is a passive process, meaning it does not require energy. Molecules move around randomly, but their net movement will be from high to low concentration, until an equilibrium is reached. This movement occurs across a partially permeable membrane. Diffusion is important for the movement of substances in the body. For example, the movement of oxygen from the lungs to the blood, and carbon dioxide in the opposite direction.