Exchange & Transport

A specialised area adapted to make it easier for molecules to cross from one side of the surface to the other.

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  • Created by: Hana
  • Created on: 21-09-12 10:21

Special surfaces for exchange

Why do organisms need special exchange surfaces?

They need special exchange surfaces to live because all living cells need ceratin substances to keep them alive:

  • Oxygen-for aerobic respiration
  • Glucose-for energy
  • Proteins-for growth and repair  
  • Fats- for making membranes and to be a store of energy
  • water
  • minerals to maintain water potential

G  LUCOSE

O  OXYGEN

M  INERALS

P  ROTEINS

 

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Special surfaces for exchange

F ATS

W ATER

What do exchange surfaces look like?

  • Large surface area to provide more space for molecules to pass through.
  • Thin barrier to reduce diffusion distance.
  • Fresh supply of molecules on one side to keep concentration high
  • removal of required molecules on the other side to keep the concentration low.

( last 3 important for a steep diffusion gradient)

(http://www.google.co.uk/imgres?q=exchange+surfaces+biology&um=1&hl=en&sa=N&biw=994&bih=638&tbm=isch&tbnid=kJExzetoSb0CiM:&imgrefurl=http://ww)

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Special surfaces for exchange

Examples of specialised exchange surfaces:

  • Small intestine where nutrients are absorbed
  • liver where sugars in the blood are adjusted
  • root hairs of plant where water and minerals are absorbed
  • hypae of fungi where nutrients are absorbed
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