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Investigating osmosis inside a potato with different concentrations solutions.

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Biology Coursework Aim: Investigating osmosis inside a potato with different concentrations solutions. A little about Osmosis: Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low concentration. 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, and carbon dioxide to pass through. Cell membranes will not allow larger molecules like Sucrose to pass through If the medium surrounding the cell has a higher water concentration than the cell, the cell will gain water by osmosis. Water molecules are free to pass across the cell membrane in both directions, but more water will enter than leave the cell. The overall result is that water enters the cell and the cell swells up. If the medium has a lower concentration of water than the cell, the cell will lose water by osmosis. Again water crosses the cell membrane in both directions, but this time more water leaves the cell than enters it. ...read more.


Also we will be careful while cutting out the potato to make sure we don't cut our fingers. Fair Test: I will make this experiment a fair test by cutting the same size potato slices, also measuring them before and after the experiment. I will also measure all the solutions so that they are all the same amount. Finally I will dry off the excess water of the potato slices before I weigh the potatoes. Results Table What the potato slices weighed before the experiment: Slice for water - 6.40g Slice for 0.4m sucrose - 6.34g Slice for 0.6m sucrose - 6.66g Slice for 1m sucrose - 6.45g Slice for 2m sucrose - 6.66g Water 0.4m 0.6m 1m 2m Potato Finish Difference Fini Diff Fini Diff Fini Diff Fini Diff Normal 6.81 + 0.41 6.25 -0.09 6.52 -0.14 6.30 -0.15 6.43 -0.23 Diced 6.50 +0.10 6.22 -0.12 6.42 -0.24 6.09 -0.36 6.13 -0.53 Graph The graph below shows what happened to the normal potato pieces and the diced potato pieces when they were left in different concentrated solutions for 15 minutes. ...read more.


The potatoes mass should not have increased that much which is shown on the graph. We didn't really have any problems with the experiment. The only problem we had was that all out potato pieces did not weigh exactly the same, which affected our results slightly. The reasons for this were we had to rush a bit and also the weighing scales were not that accurate. If the pieces all weighed the same our results would have been more obvious. This is because the rate of osmosis would have been clearer, as the pattern of mass changes would be easier to see. There are improvements we can make to make the results more accurate next time. Firstly we can take more time on weighing the potatoes and measuring the solutions so we can make sure that the experiment is fair as possible. Secondly we can keep the potato pieces in the solutions for longer (maybe 30 mins) so are results can be improved. Thirdly we can repeat the results for both the different cut potatoes. We can get an average reading and our results will be much more accurate. ...read more.

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