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The effects of osmosis in potato cells.

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Introduction

Biology Science Investigation Title: The effects of osmosis in potato cells 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 is the passage of water molecules from a weaker solution into a stronger solution, through a partially permeable membrane. In this case, the tiny holes in 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. So in this case, when the water concentration is lower in the tissue, the later will go inside the tissue of the potato, and the potato will gain mass. If there is very little different in the two water concentrations, there shouldn't be such a big change in mass. Also if there is a higher concentration of water in the potato, then the water will go out of the potato and into the liquid solution, as osmosis is the movement of water molecules from a region of high concentration to a region of low concentration, through a partially permeable membrane. Planning Variables: There are many many variables that can be altered. These include: * Mass of chips in grams * Dimension of chip in cm * Strength of surcose solution in moles * Volume of sucrose solution in ml * Temperature of surcose solution in degree's centigrate * Type of potatoe * Length of time in hours * Location ie. ...read more.

Middle

Artificial partially permeable membranes are made from cellulose acetate in sheets or tubes and used for dialysis rather than for osmosis. The pore size can be adjusted during manufacture so that large molecules cannot get through at all. The cell membrane behaves like a partially permeable membrane. The partial permeability may depend on pores in the cell membrane hut the processes involved are far more complicated than in an artificial membrane and depend on the structure of the membrane and on living processes in the cytoplasm. The cell membrane contains lipids and proteins. Anything, which denatures proteins, e.g. heat, also destroys the structure and the partially permeable properties of a cell membrane. If this happens, the cell will die as essential substances diffuse out of the cell and harmful chemicals diffuse in. Fair test: To make this experiment a fair test I will use the same... Length potatoes- so that there is the same length of potato for osmosis to take place in. Room temperature- so that this doesn't affect the rate of reaction. Size cork borer- so that the size of the potato doesn't vary. Amount of sugar water- so that the potato pieces have no more or less sugar solution to absorb. Amount of time potatoes are left in sugar solution. - so that I can record accurate results. ...read more.

Conclusion

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. Repeating the same tasks many other times wouldn't have been very useful, since we had already done the result 3 times, and ALL the results were reliable. Even though we didn?t use these experimental plans, we still got results which were correct, according to my hypothesis, and backed up my predictions. But overall, given the apparatus that we got to carry out the test, I think this experiment turned out to be very successful, and Im very please with my results.There is a positive correlation . ?? ?? ?? ?? John McArthur ...read more.

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