Osmosis

Osmosis in potato chips

The aim of this investigation is to find out what salt concentration potato cells are and to find this out I will be using osmosis.

Osmosis is when water from an area high concentration moves to an area of low concentration through a semi-permeable membrane.



Semi-permeable membranes are very thin layers of material (cell membranes are semi-permeable) which allow some things to pass through them but prevent other things from passing through. Cell membranes will allow small molecules like Oxygen, water, Carbon Dioxide etc. to pass through. Cell membranes will not allow larger molecules like Sucrose, Starch, protein, etc. to pass through.

When you put a animal or a plant cell in a solution of high concentration (a solution which is very dilute) one of these three things will happen.

If the cell has a lower concentration then the solution its placed in the cell will gain water through osmosis. Water molecules can pass across the cell membrane in both directions, but more water will come into the cell than will leave.

If the cell has the same concentration as the solution its placed in the cell will not gain or lose water through osmosis

If the cell has a higher concentration than the solution its placed in the cell will loose water through osmosis. Again, water crosses the cell membrane in both directions, but this time more water leaves the cell than enters it.

Plant cells have a strong cell wall. When plants take up water by osmosis the cells start to swell, but the cell wall prevents them from bursting. Plant cells become "turgid" when they are put in dilute solutions. Turgid means swollen and hard. Turgidity is very important to plants because