Gas and Solute Exchange

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  • Created by: Georgia
  • Created on: 22-04-13 19:20

Substances move by Diffusion, Osmosis and Active Transport

  • Life processes need gases or other dissolved substances to happen
  • e.g. For photosynthesis to happen, carbon dioxide and water have to get into plant cells.
  • e.g. For respiration to take place, glucose and oxygen both need to get into cells
  • Waste substances need to move out of cells so the organism can get rid of them
  • These substances move to where they need to be by diffusion, osmosis and active transport:
  • Diffusion - where particles move from an area of high concentration to area of low concentration
  • e.g. gases can diffuse through one another, like smell spreading through a room
  • Alternatively, dissolved particles can diffuse in and out of cells through cell membranes
  • Diffusion and osmosis both involve stuff moving from area of high concentration to area of low concentration.
  • Sometimes substances need to move in the other direction - active transport
  • In life processes, gases and dissolved substances have to move through some sort of exchange surface.
  • The exchange surface structures have to allow enough of necessary substances to pass through
  • Exchange surfaces and adapted to maximise effectiveness:
  • They


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