B2 - diffusion
- Created by: Charlotte
- Created on: 08-04-13 17:06
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- Diffusion
- Molecules in gases and liquids move around randomly because of the energy they have
- Diffusion is the spreading out of the particles of a gas, or of any substance in solution
- Because the particles move randomly, there will be a net(overall) movement from an area of high concentration to an area of lower concentration
- The net movement into or out of the cells depends on the concentration of the particles on each side of the cell membrane
- The difference in concentration is called the concentration gradient
- The larger the difference in concentration, the faster the rate of diffusion
- Examples of diffusion:
- the diffusion of oxygen into the cells of the body from the bloodstream as the cells are respiring (and using up oxygen)
- the diffusion of carbon dioxide into actively photosynthesising plant cells
- the diffusion of simples sugars and amino acids from the gut through cell membranes
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