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In my experiment, I am trying to find out how the concentration of a sucrose solution which pieces of potato are placed in affects how the mass of the potato changes due to osmosis.

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Biology coursework How does the concentration of a solution affect change in mass caused by osmosis? Plan Osmosis is the diffusion of water form a dilute to a concentrated solution of water. Cell membranes are partially permeable, which means water molecules fit through, but other, larger molecules such as glucose or sucrose (as in my experiment) cannot. When cells are placed in an extremely dilute solution, water rushes into the cell, which causes the cell to become swollen. When they are placed in an extremely concentrated solution (more concentrated than the solution inside of the cell), water moves out of the cell, causing them to become shrivelled. Either of these extremes can be dangerous to the cell, causing them to be damaged and stop working properly, or even burst and die. In my experiment, I am trying to find out how the concentration of a sucrose solution - which pieces of potato are placed in - affects how the mass of the potato changes due to osmosis. I conducted a preliminary experiment first, to decide how to do my experiment. I measured 10mm lengths of a 5mm diameter potato core, and placed them in 10cm3 solutions of various concentrations. ...read more.


* The potato cores are all the same shape as well as the same weight, so they have the same surface area, in case it has any affect. * Remove all the pieces of potato after the same amount of time, so none of them undergo osmosis for longer than any of the others. * Use the same syringe to measure out the water and sucrose solution so that if the syringe has any imperfections in its accuracy they will at least be consistent for the whole experiment. * Use the same scales to measure every piece of potato, before and after the experiment. Similarly, if the scales have any imperfections, these will be consistent throughout the whole experiment. * Use sucrose solution from the same bottle in case it has been contaminated and the concentration is not exactly correct, so it will not affect the results. * Use cores from the same potato so there are no differences in the sucrose concentrations of each potato core before the experiment. Results % sucrose 0% 20% 40% 60% 80% 100% Weight after experiment Repeat 1 1.37 1.14 1.13 0.97 0.85 0.77 2 1.33 1.16 2.06 0.95 0.84 0.75 3 1.41 1.09 1.10 0.96 0.84 0.77 Mean 1.37 1.13 1.10 ...read more.


My results were quite accurate and there were not many big improvements I would need to make to improve my method and equipment. The lower three percentages have relatively large error bars, compared to the upper three percentages. I cannot think of an explanation for this, except perhaps there was less human error when weighing the last three because me and my group got more experienced with using our temperamental scales accurately. The only error bars which overlap are those for 20% and 40%, which I believe is due to the outlier of 20%. This means most of my results show a real difference, and there are enough accurate results not including those for 2-%, that I believe my experiment still shows a real pattern. Overall, I am very confident in my conclusion. My method was good, and there are very few major improvements, and a small number of minor ones that I would make if I did the experiment again. My equipment and setup was the weakest area of my experiment, sue to the poor setup of placing the repeats in the same solution, and the slightly temperamental scales I used. However, my data is fairly reliable, and mostly has small error bars which do not overlap and are close to the line of best fit. So overall, I think my conclusion is true and reliable. ...read more.

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