SA:Vol

  • Created by: Hindleyc
  • Created on: 01-06-18 10:55
What does an organisms requirement to obtain materials depend on?
Its metabolic rate
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What does metabolic activity increase with?
Volume
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What does the rate of exchange of substances and heat depend on?
The organisms SA
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What substances must all organisms exchange with their surroundings?
Food, waste, gases and heat
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What must these substances do?
Diffuse between the organisms and the surroundings
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What is the rate at which a substance can diffuse given by?
Ficks law- SAxConc difference / distance
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What does the ability to meet the requirements depend on?
The surface area: volume ratio
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What happens as an organism gets bigger?
SA:vol decreases as volume increases more than SA
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What happens with a small SA and relatively large volume?
Rate of diffusion and heat exchange low so difficult to exchange substances with their surroundings
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What adaptations increase SA?
Folding/branching, Longer/thiner/flat,
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What other adaptations to inc rate?
Maintain high conc gradient and minimise distance over which exchange occurs
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What does a small SA:Vol ratio mean?
Lose less heat than small animals
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What do large mammals do?
Keep warm quite easily and don't need much insulation or heat generation
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What do small mammals and birds do?
Lose heat very readily so need high metabolic rate in order to keep generating heat along with thick insulation- feed continuously
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When you lose heat quickly to the surroundings you..
Have to respire quickly to generate heat to replace what is lost.
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What must they do then?
Consume more food and oxygen per unit of body weight than larger animals (high H.R)
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Other cards in this set

Card 2

Front

What does metabolic activity increase with?

Back

Volume

Card 3

Front

What does the rate of exchange of substances and heat depend on?

Back

Preview of the front of card 3

Card 4

Front

What substances must all organisms exchange with their surroundings?

Back

Preview of the front of card 4

Card 5

Front

What must these substances do?

Back

Preview of the front of card 5
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