Diffusion and Osmosis
- Created by: erinmcmenamy23
- Created on: 05-12-15 21:58
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- Diffusion and Osmosis
- Diffusion
- It is how gas exchange occurs in the lungs and the leaves of plants
- The movement of molecules from an area where they are in a high concentration to an area where they are in a lower concentration along a concentration gradient
- Osmosis
- A special type of diffusion involving the movement of water molecules through a selectively permeable membrane
- A selectively permeable membrane allows small molecules such as water through but not larger molecules such as sugar
- Visking tubing is an example of an artificial selectively permeable membrane
- Cell membranes are selectively permeable
- A selectively permeable membrane allows small molecules such as water through but not larger molecules such as sugar
- Solution
- Dilute solution - lots of water
- Concentrated solution - less water
- If the concentrations of the solutions inside and outside the cell are different - osmosis will occur
- How osmosis affects living organisms
- The cell wall prevents the cell taking in too much water
- the cell can become plasmolysed - the cells lose so much water that the membrane pulls away from the cell wall
- Osmosis in animals
- Cells are usually in carefully controlled conditions and they do not take in or lose too much water
- A red blood cell will shrivel up in a strong sugar solution or burst if placed in pure water
- A special type of diffusion involving the movement of water molecules through a selectively permeable membrane
- Diffusion
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