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Investigating Osmosis

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Introduction

Investigating Osmosis Aim: *- Investigating osmosis by monitoring the effect of water concentrations on the mass of potato tissue. Preliminary work: *- Before I started this experiment I previously conducted a simple procedure to confirm a suitable range of readings. I used salt solutions of concentrations 0%, 10%, 50%, 90% and 100%. From my findings, there were variations between concentrations 0% and 50%, however, beyond these concentrations, there were no variations that occurred. I was pleased with these results as they were consistent with my prediction and agreed with what I had already learnt about osmosis. However I was disappointed with my results which I had obtained, due to the fact that I provided myself with a limited range of concentrations which did not successfully give me an in depth scope on the whole experiment in hand. I have therefore decided to use salt solutions, varying in concentrations between 0% and 5%, (1% concentration = 1g of salt in a litre of water). Method: > Prepare the equipment/apparatus, which are going to be used in the experiment. > Use the knife to peel the potato. > Use the tile to cut the potato into small chips with the scalpel. ...read more.

Middle

The smaller the concentrations of water in the external solution the greater the amount of water that leaves the cell. Many variables effect osmosis. These variables include: Temperature Volume of a solution Concentration Weight of potato Surface area I have chosen to change the concentration because I hope this will give me a good varied set of results to work with. The concentration will be measured in ml. Prediction: *- I predict that at first the mass of the potato tissue will increase, however, as the concentration of salt in the solution increases past a certain point the mass of the potato chips will decrease. Water particles pass from a high concentration to a low concentration through the uptake of water through a semi-permeable membrane. I predict that the lower the concentration of the salt solution in the test tube the larger the length of the potato will be. So in a high salt concentration the potato will have a smaller length. You see When you put an animal or plant cell into a liquid containing water one of three things will happen: *- If the medium surrounding the cell has a higher water concentration than the cell (a very dilute solution) ...read more.

Conclusion

A final obstacle was that some of the chips remained in the solution while measured the others, an partial answer to the problem would be to empty all of the chips out of the petri dishes first, then measure them all at once. In terms of expanding my investigation, I could introduce other variables such as temperature (Would osmosis slow down or even fail to occur in the low temperature of a refrigerator?) or the weight of the chip (Would the weight of the potato chip affect the speed of osmosis or prevent it from occurring at all and would a potato chip cut in two react differently when compared with a regular chip?)or even comparing the results yielded by a) one or two chips in separate test tubes and b) one or two chips in the same solution, the possibilities are endless. There was always a chance that the potato that I used was abnormal so a good idea would be to test a series of potatoes. It would be interesting to investigate whether or not other varieties of potato yield different results and trends. And why stop at potatoes? Why not try other similar vegetables such as sweet potatoes, carrots, turnips and parsnips. By Tyrone Sinclair 1 Tyrone Sinclair ...read more.

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