• Created by: Lena Fray
  • Created on: 14-09-15 19:53


Diffusion: the spreding of particles from an area of high concentraction to low concentration.

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Changing rate

Speeding up: 

  • Heat the particles
  • Bigger the difference in concetration => Faster the rate of diffusion
  • Moist Surfaces
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Can happen in: 

  • Open spaces
  • Cell membrances
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Across Membrances

Diffusion across membranes: 

  • Small molecules are able to pass through eg. co2, O2
  • Thin/ partically permable membrances
  • Diffusion goes both ways => passive procces
  • Large concentration gradient
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Osmosis: The movement of water across a partially permable membrane from on area of high concentration to low concentration.

Osmosis diagram (http://mrphome.net/mrp/_reffiles/osmosis%20animation.gif)

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Active Transport

Active Transport: 

  • The movment of substances across cells 
  • Against a concentration gradient => goes from low to high
  • Moves a subsatnce through the cell
  • Uses energy => biological
  • Protiens move substances by changing shape
  • Protien channels and protiens are randomly distbuted
  • Active Transport diagram
  • (http://i.stack.imgur.com/4JjWh.gif)
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