6.1- Exchange between organisms and their environment

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  • Created by: Megan2413
  • Created on: 02-02-17 21:00
What does the surface area : volume ratio have to be like for diffusion to be effective?
The exchange surface of the organism needs to be large compared to its volume. The higher the surface area : volume ratio is the faster the rate of diffusion
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What is fick's law?
Diffusion is directly proportional to (surface area x difference in concentration) divided by length of diffusion pathway
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What two evolutions have various organisms developed for effective gas exchange?
- A flattened shape so that no cell is ever far away from the surface - Specialised exchange usrfaces with large areas to increase the surface area to volume ratio
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How do fish increase their surface area to volume ratio?
By having gills
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What four factors affect diffusion?
- temperature - Differences in concentration - Surface area - Thickness of surface
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State three features of specialised exchange surfaces
- Large surface area : volume ratio - Thin surface to exchange substances quickly - Selectively permeable to allow selected materials to cross - Movement of the environment medium (e.g. air to maintain diffusion gradient) -->
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Transport system to ensure the movement of the internal medium, for example blood, in order to maintain a diffusion gradient
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Organisms with a high metabolic rate exchange more materials and so require what?
A larger surface area : volume ratio
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Card 2

Front

What is fick's law?

Back

Diffusion is directly proportional to (surface area x difference in concentration) divided by length of diffusion pathway

Card 3

Front

What two evolutions have various organisms developed for effective gas exchange?

Back

Preview of the front of card 3

Card 4

Front

How do fish increase their surface area to volume ratio?

Back

Preview of the front of card 4

Card 5

Front

What four factors affect diffusion?

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