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Show the action of water moving in and out of cells (Osmosis) by using potatoes.

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Aim To show the action of water moving in and out of cells (Osmosis) by using potatoes. Background Science/Previous work I have done work on Osmosis before in school on carrots, potato chips and grapes. Osmosis is the action of water from a region of high water concentration to pass through a semi-permeable membrane to a region of lower water concentration. The speed of which Osmosis takes place varies on the difference in the two concentrations. If there is a higher concentration of water in the medium surrounding a cell, the cell will gain water by Osmosis. Although water molecules will still be able to pass across the cell in both directions, more water will enter the cell than will exit. The net result to the process is that water will enter the cell. It is likely that the cell will swell up. If there is the same concentration of water on the outside of the cell as well as the inside then water will still be passing over the membrane but the cell will stay roughly the same shape and size. If there is a lower concentration of water in the medium surrounding the cell, the cell will lose water by Osmosis. As above, water will still pass over the membrane but it will end up with less water. Plant and Animal cells have many differences about them and have some different consequences due to Osmosis happening. ...read more.


0ml Dis. Wat. 20ml Salt Sol. Prediction My hypothesis is that the potato strips sharing the test tubes with a less amount of salt solution will swell, increasing in mass and length. The potato strip sharing the test tubes with a higher amount of salt solution will shrink, decreasing in mass and length. Outcome The measurements that I will be collecting from my experiment will be the change in mass and length. The change in mass proves that the cells have lot water, and the change in length proves that they have become flaccid of turgid. Apparatus Apparatus Potatoes Salt solution(1m) Distilled water Measuring cylinder Knife Cork Borer Cutting Board Test tube Test Tube Rack Boiling Tubes 100cm3beakers Labels Weighing scales (sensitive) Ruler Quantity 1 2 2 1 1 1 1 10 2 - 2 15 1 1 Method * ! At no time should the potato be consumed in, or if it has been in the laboratory, it may have picked up unhealthy germs that have previously been worked with ! * !Lab coats should be worn for extra protection ! 1) Take one test tube rack and place 5 test tubes into it. Label the set of test tubes Test 1. 2) Using the measuring cylinder, put the allocated amount of salt solution and water shown in the input variable section of this project into each test tube. ...read more.


-0.45 5 4cm 3.45cm -0.55 These results show that the Percent change in mass and length decrease as a higher amount of salt is added to the solution; however, it would be easier to recognize and appreciate this decrease by plotting the points onto a line graph. Conclusion The results from the experiment show that in the test tubes with the majority of water, the potato chip inside them swelled, and the potato chips inside the test tubes with the majority of salt solution in them shrunk. In the balanced test tube (Distilled water and Salt solution are the same quantity), there was very little change in the mass and length of the chip. This proves my Hypothesis correct, and is a very good example of the action of Osmosis. Evaluation The experiment went very well, and according to plan, I proved all of the things that the experiment was produced for. However, there are a few things that I did not feel were completely acceptable, and would have changed if I now had the chance. One of these things was the range of solutions that I used. Using only five, I did not feel that the results were 100% accurate. I would have preferred to do about 10 to be completely accurate. I would have also have liked to talk more on the subject of previous experiments that I have done, to give a complete understanding of Osmosis. Samuel Verlander Biology Coursework GCSE 2004 ...read more.

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