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Practical to find out the concentration of cell sap.

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01/10/01 Practical to find out the concentration of cell sap by Emma Walters Aim: My aim is to find the concentration of cell sap. Apparatus: * 1m sugar solution * distilled water * 6 boiling tubes * 2 test tube racks * ruler * measuring cylinder * balance * cork borer * 18 pieces of potato * stop clock * paper towels * scalpel Diagram: Method: 1. In the six boiling tubes, sort out the 6 different concentrations with the components: * 1m - 20ml sugar solution * 0.8m - 16ml sugar solution, 4ml distilled water * 0.6m - 12ml sugar solution, 8ml distilled water * 0.4m - 8ml sugar solution, 12ml distilled water * 0.2m - 4ml sugar solution, 16ml distilled water * 0m - 20ml distilled water 2. Use the cork borer to cut the potatoes into 18 pieces. 3. Put them into groups of 3, so there are 6 groups. 4. Dry all the pieces of potato off, so that when you weigh and measure them it is a fair test. ...read more.


I have tried to draw a line of best fit from the results, and as you can see from the weight results, the concentration of cell sap should be 0.57m. From the length results, the concentration of cell sap should be 0.41m. The average of these is 0.485m, so this should be the concentration of the cell sap in a potato. As I said in my prediction, if the solution is isotonic, the potatoes weight and length should stay the same, and this nearly happened, as for the 0.6m solution, the length of the potato did not change, but the weight did by only 0.2g. This could have been partly to me weighing them wrong, or not leaving them in long enough, but this solution was nearly isotonic. If the solution was Hypotonic, the potatoes length and weight should have gone up. For the solutions 0.2m and 0m, this happened, as they were hypotonic solutions. The Hypertonic solutions, 1m and 0.8m should have lost weight and gone down in length, as they did. ...read more.


The amounts of the solutions I thought were quite accurate, but when you put the boiling tubes next to each other, you could tell that some solutions had slightly more in than the next. This could also have affected my results. Not only this, but I do not think that I left the potatoes in the solutions for long enough for them to conduct osmosis to a reasonable degree of accuracy. I think that this was my biggest error that affected my results the most, and this is why the information that I got was not as good as it potentially could have been. If I were to do this experiment again, this time I would make sure that I am more accurate with all my measuring and weighing, and that I leave the potatoes in the solutions for over 15 minutes, so that they have time to conduct osmosis. This should make my results reliable and accurate, and let me get a better graph. This should also mean that I get a more accurate result for the concentration of cell sap. ...read more.

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