B3 - Osmosis

B3 - Osmosis

1. 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

   • Partially permeable membrane- small holes in it, only small molecules can pass throught it
   • Water molecules pass both ways through the membrane. This is because they move randomly all the time.
   • So a strong sugar solution would become more dilute.

2. Type of diffusion. Passive movement of water molecules.

3. Water moves into and out of cells be osmosis.

4. Tissue fluid surrounds the cells in the body. It will usually have a different concentration to the fluid inside a cell so water will move in and out by diffusion.

5. If a cell is short of water, the solution inside will become concentrated so the outside is more dilute so water will move into the cell by osmosis. If a cell has lots of water, the solution inside will be more dilute so watwer will be drawn out of the cell and into the fluid by osmosis.