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9 Cards in this Set
- Front
- Back
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What is the definition of diffusion? |
The net movement of particles from an area of high concentration to a low concentration. |
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Is diffusion active or passive? |
Passive - doesn't need energy. |
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What is the aim of diffusion? |
To try and get it equal concentrations - isotonic. |
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What is the type of diffusion called when molecules can diffuse directly through the membrane down the concentration gradient? |
Simple diffusion. |
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Name 3 factors which affect simple diffusion. |
Concentration gradient - higher = faster. Thickness of exchange surface - thinner = faster. Surface area - larger = faster. |
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Define facilitated diffusion. |
Net movement of larger, water-soluble, ions and polar molecules from an area of high concentration to an area of low concentration using channel or carrier proteins. |
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How do carrier proteins work? |
Move molecules down concentration gradient. Molecule attaches to carrier, it changes shape then releases the molecule on the opposite side of the membrane. |
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How do channel proteins work? |
Down concentration gradient. They form 'pores' in the membrane for charged molecules to diffuse through. Different channel proteins facilitate different particles. |
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Name 2 factors which affect facilitated diffusion. |
Concentration gradient - higher = faster. Number of proteins - once they're all in use the rate cannot increase any more. |
