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See the results of a potato tissue's mass difference, when placed in different concentrations of sugar solutions.

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Introduction

Investigating Osmosis Aim My aim for this experiment is to see the results of a potato tissue's mass difference, when placed in different concentrations of sugar solutions. Osmosis Explained Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration. It can be affected by several different variables including concentration of sugars. In this investigation I will be exploring the effect of varying concentration of sucrose sugar solution on the amount of osmotic activity between the solution and the potato chip of a given size. Osmosis is basically a special kind of diffusion involving water molecules, which occurs when two solutions are separated by a partially permeable membrane. The water diffuses from the weaker solution to the stronger solution. Tiny holes in the membrane allow small water molecules to pass through, but the glucose molecules are too large to pass through the semi- permeable membrane. Plant cells have a cell wall surrounding them, this is very strong. When they take in water by osmosis they begin to swell, but the cell wall stops them bursting. Plant cells become swollen and hard when they are put in dilute solutions. The pressure inside the cell will rise and eventually is so high no more water can enter the cell. ...read more.

Middle

Apparatus Apple corer - to cut circular potato pieces Potatoes - to use to show osmosis Kitchen towel - to dry potato pieces, so water does not make them weigh more, as this would not make it fair 5 test tubes - to put the solution in Sucrose solutions - to put potatoes in, 5 different concentrations Test tube rack - to put test tubes in Pen, Paper and ruler - to record results Electronic balance - to weigh potato pieces, gives a more accurate result than normal balance Method 1. Take 2 similar sized main-crop potatoes. 2. Carefully use an apple corer to make circular sections approx. 2cms long. 3. Wash and dry all the pieces 4. Make a table to record results in. 5. Weigh each potato piece on an electronic balance and make sure they are a similar mass. Do this for 3 pieces at a time to ensure pieces for each solution do not get mixed up. You need to keep all the pieces together so you can keep track of which masses go into each test tube. This is important to keep the experiment a fair test. 6. Take a test tube rack and place 5 test tubes in it. Label them 0 molars, 2 molars, 4molars, 6molars, 8molars and 10molars 7. ...read more.

Conclusion

To make this experiment better, I believe that we could have done one test at a time, so that we can reduce the time difference, when we have to move the potato from the test tube to the balance. Between this, we have to dry the potatoes just enough, and then put it on the balance. When we are doing this for one set, writing down the results at the same time, while the other 5 sets are on the tissue paper, the water outside the potato tissue is going to vary for all. Therefore, we would be able to concentrate more on one of the sets, instead of trying to finish all of them as quickly as we can. We also could have got more people to do the experiment with us, so that we can organize the tasks, and we would be able to divide the tasks. Using more types of molar sucrose solutions would have helped us obtain better results, and more accurate results, so that we can make sure the results are totally correct. Experimenting with one set for a longer period of time, for each set, would lead us to better results, because the osmosis action would reach its maximum capability, and therefore tell us how much water could be transferred for each solution. Overall I am very pleased with my investigation and the way I carried it out. By Jack Butcher 26/04/07 ...read more.

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