Biology

Movement of water molecules across partially permeable membrane from high water concerntration to region of low water concerntration.

Partially permeable membrane, very small holes in it, only tiny molecules fit through (water) big molecules can't (sucrose).

Water molecules move randomly both ways through membrane.

More water molecules on one side means steady net flow of water in the region with fewer water molecules.

So strong sugar solution gets more dilute, water evens up concerntration.

Type of diffusion, passsive movement of water particles from high water concerntration to area of low water concerntration.

 

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Osmosis

Movement of water molecules across partially permeable membrane from high water concerntration to region of low water concerntration.

Partially permeable membrane, very small holes in it, only tiny molecules fit through (water) big molecules can't (sucrose).

Water molecules move randomly both ways through membrane.

More water molecules on one side means steady net flow of water in the region with fewer water molecules.

So strong sugar solution gets more dilute, water evens up concerntration.

Type of diffusion, passsive movement of water particles from high water concerntration to area of low water concerntration.

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Movement of water in and out of cells by Osmosis

Tisssue fluid, surrounds cells in body, (water, oxygen and glucose) squeezed out of blood capillaries, supplys cell with everything they need.

Tissue fluid will have a different concerntration to the fluid inside cell. So water will move into the cell from tissue fluid or out of the cell by osmosis.

If a cell is short of water, the solutution will become quite concerntrated, so the solution outside is usally more dilute, so water will move into the cell by osmosis.

If the cell has lots of water, solution inside will be more dilute, water will be drawn out of cell into fluid outside by osmosis.

Experiment, cut up potato identical cylinders, get two beakers with different sugar solutions, one pure water, another very concerntrated sugar soloution. Measure length of cylinders, leave the cylinders in beaker then measure the lenght again, if the cylinders have drawn in water by osmosis they will  be longer, if water has been drawn out it would have shrunk. Dependant variable: chip length. Independant variable: concerntration of sugar soloution. All other variable stay the same for fair test.

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