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To discover how the weight a potato chip is affected when induced to varying molars of glucose.

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BIOLOGY COURSEWORK Aim: To discover how the weight a potato chip is affected when induced to varying molars of glucose. Prediction: I predict that in pure water, the potato chip will become turgid and its weight will increase. In an isotonic solution the potato will stay the same weight, and anything above the isotonic level will make the potato chip flaccid and the weight will decrease. Reason: Osmosis is the passage of water molecules from a weaker solution into a stronger solution, through a partially permeable membrane. In this case, the membrane of the potatoes will allow the water molecules to pass through in and out of the solution and the potato, depending on the concentration gradient of the two substances. When the sugar concentration is lower in the tissue, the water will go out of the tissue of the potato, and the potato will lose weight. If there is very little different in the two water concentrations, change in weight should be negligible. And if there is a higher concentration of sugar in the potato, the water moves into the potato by osmosis and increases its overall weight. In the distilled water, I believe that the sugar is more concentrated in the potato, and therefore the water should transfer from the water to the potato, making the potato bigger in size, and heavier in weight. ...read more.


First I will have to get the pieces of potatoes ready. I will push the cork borer through the potato, cutting it into long cylinders with a diameter of 6mm. And then I will cut the potatoes into cylinders of 40mm, and weigh 3 sets of 5 potato cylinders. I will have 3 sets so at the end I can take an average and I will be able to spot any anomalies. I will have 3 test tubes of each different molar of glucose mixed with water, which shall be 0.0, 0.5, 1.0, 1.5, and 2.0. This works out as 20ml water, 15ml water + 5ml glucose, 10ml water + 10ml glucose, 5ml water + 15ml glucose, and 20ml glucose respectively. I will weigh each set and have them ready for us to put into the test tube. Then we will put the 3 sets of 5 potatoes in the 15 test tubes at the same time, and then leave them over night. The next day, we will take all of the potatoes out of the test tube, so that the actual osmosis action stops, and we will dab the potato chips dry on sheets of dry paper towel, keeping record of which one is which. We will then weigh the potatoes taking in the average reading of the 3 sets. ...read more.


To make this experiment better, I believe that when we have to move the potato from the test tube to the balance we should try and do this as quickly as possible. We also 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 3 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. Using more types of molar sucrose solutions would have helped us obtain better results, and more accurate results, and given us a better idea of where the isotonic point was, 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. Even though we didn't use these experimental plans, we still got results which were correct, according to my prediction. Overall, given the apparatus that we got to carry out the test, I think this experiment turned out to be very successful, and I'm very please with my results. Sam Badger 11D1 ...read more.

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