The meaning of diffusion

The rate of diffusion

  • Created by: Tom
  • Created on: 17-05-10 12:18


Diffusion is the passive movement of particles from an area of high concentration to an an area of low concentration.

  • Particles go through the cell membrane from where there are more particles (high concentration) to where there are less particles (low concentration)
  • Particles move randomly so they go both ways, but the most movement tends to be away from the area of high concentration.
  • The rate of diffusion is affected by the concentration difference. Substances diffuse faster if there is a bigger concentration difference, if there are lots more on one side then there are more to move across.
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Osmosis is the movement of water molecules through a partially permeable membrane, from an area of high water concentration to an area of low water concentration.

  • Water moves in and out of cells by osmosis.
  • Tissue fluid is water with oxygen, glucose and other nutrients dissolved inside it.
  • Through osmosis this water gets into the cell (via the membrane) because the cell has a low concentration of oxygen, glucose.
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