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Biology

Cells and diffusion

Osmosis

Osmosis is the net movement of water from a high water concentration to a low water concentration across a membrane. In this video osmosis is explained with the help of a large net and a crowd of human volunteers.

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Key points

  • Cell membranes are selectively permeable.
  • Water is able to move across membranes by the process of osmosis.
  • Osmosis is the net movement of water from an area of high concentration to an area of low concentration through a selectively permeable membrane.
  • Plants use osmosis to take up water into their roots and this makes the cells firm or turgid.
  • Animal cells have no cell wall and so there is a danger they will burst if they take in too much water.
  • Animal cells shrivel up if they lose too much water.

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