B2(i) - Life Processes 4.

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Osmosis Is a Special Case of Diffusion.

OSMOSIS is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration.

1) A partially permeable membrane is just one with very small holes in it. So small only very small molecules like water can get through them, and bigger molecules like sucrose doesn't have a chance.

2) The water molecules actually pass both ways through the membrane during osmosis. this is because water molecules move about randomly all the time.

3) However because there are more water molecules on one side than on the other, there's a steady net flow of water into the region with fewer water molecules i.e. into the stronger solution

4) This means…


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