6.1- Exchange between organisms and their environment

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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Other cards in this set

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

Card 4

Front

How do fish increase their surface area to volume ratio?

Back

Card 5

Front

What four factors affect diffusion?

Back

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6.1- Exchange between organisms and their environment