Diffusion, osmosis and active transport
- Created by: Ashleigh Hockenhull
- Created on: 30-03-15 12:46
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- Diffusion
- the spreading of the particles of a gas or a substance in a solution
- Factors that affect the rate of diffusion
- concentration: greater the difference, the faster the rate
- distance: smaller the distance, faster the rate
- surface area: greater the surface area, the faster the rate
- Leaves are adapted so diffusion happens quickly
- leaves are thin to reduce the distance that gases have to diffuse through
- Osmosis
- type of diffusion that involves random movement of water molecules
- movement of water across a partially permeable membrane from an area of high water concentration to an area of low water concentration
- partially permeable membrane
- allows water molecles through
- stops solute molecules getting through because they are too large
- Active Transport
- allows cells to absorb sugar and ions, which can pass through cell membranes from very dilute substances
- movement of dissolved molecules into or out of a cell through the cell membrane, from a region of lower concentration to a region of higher concentration
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