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An Investigation To Demonstrate The Affect Of Different Sucrose Concentration On Osmosis In Plant Tissue

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Introduction

Biology Coursework on Osmosis Preliminary Experiment An Investigation To Demonstrate The Affect Of Different Sucrose Concentration On Osmosis In Plant Tissue Planning What I am investigating My aim in this experiment is to investigate the effect of varying concentration of a certain sugar solution on the amount of osmotic activity between the solution and a potato chip of a given size Preliminary Experiment Hypothesis: Osmosis is the movement of water molecules from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a partially permeable membrane such as a cell membrane, which lets smaller molecules such as water through but does not allow bigger molecules to pass through. The molecules will continue to diffuse until the area in which the molecules are found reaches a state of equilibrium, meaning that the molecules are randomly diffuse throughout an object, with no area having a higher or lower concentration than any other. Apparatus: * 6 boiling tubes * 3 potato chips of 2cm * electronic lab scales * 0M-1M of sucrose solution * scalpel * clay tile * measuring cylinder * stop watch * beaker * tissue paper * ruler Method: A range of sucrose sugar solutions were prepared with concentrations 0 molar (distilled water), 0.5 molar, and 1 molar. Three sections of potato were cut using a scalpel and will be measured using a ruler to both 2cm and 3cm. The mass of each chip was measured to find the mass change. The chips were placed in each test tube, using 10 cm of each concentration of sugar solution and once in the test tubes they each were labelled. The potato pieces were then be placed in the different test tubes and then left overnight, as I felt this was enough time for Osmosis to occur. Then the potato pieces were removed, the surface solution was removed using paper towels and then they were re-weighed. ...read more.

Middle

Percentage Change In Mass (%) Average Percentage Change In Mass (%) 0 4.62 5.43 0.81 17.53 16.03 0 4.28 5.09 0.81 17.53 0 5.07 5.73 0.66 13.02 0.25 5.3 5.77 0.64 12.48 10.76 0.25 5.25 5.78 0.53 10.10 0.25 5.15 5.65 0.50 9.71 0.5 5.42 4.83 -0.59 -10.89 -12.15 0.5 5.19 4.48 -0.71 -13.68 0.5 5.05 4.45 -0.60 -11.88 0.75 5.29 6.05 -0.76 -14.37 -13.84 0.75 4.92 5.62 -0.70 -14.23 0.75 4.72 5.33 -0.61 -12.92 1 4.22 5.22 -1.00 -23.70 -27.6 1 4.49 3.54 -0.95 -21.16 1 4.77 2.96 -1.81 -37.95 Analysing and Considering Evidence What My Graph Shows On my graph I have decided to plot the average percentage change in mass against the concentration in Molars. I have made the sucrose solution measured in Molars on the x axis and the average percentage change in mass (%) on the y axis. I have decided to make the graph with a line of best fit as it effectively shows the anomalous result and the trend in which Osmosis in a potato chip occurs. The obvious trend in my line graph shows as the concentration of molars increases so that the average change of mass in the potato decreases. At O molars (distilled water) the average change in mass of the potato chip increases by 16.03%. At 0.25Molars of sucrose solution the average change in mass is still positive but not as much; it increased by 10.76, this was anomalous, as the average percentage change in mass of the chip was too high; the result here were above the line of best fit. At 0.5 molars of sucrose solution the change in the average mass decreased as the water molecules went out of the potato due to the sucrose solution having a lower concentration of water compared to the inside of the potato cells; the result here was at -12.15%. By 0.75 Molars, the average change in mass of the potato should have decreased in mass, but it increased compared to the result at0.5M; the average change in mass of the potato chip was at -13.84. ...read more.

Conclusion

Then, I would make sure, that when each potato chip was dried to remove excess water, it was done fairly, by drying the chips all at once, in this way all of the chips are treated in the same manner. I would further measure the diameter change of the potato, which would help me to find out the volume before and after of the potatoes, as when a chip is turgid it increases in size as well as in mass, and when the chip is flaccid it decreases in size as well as mass. In this way I would be able to find out how far Osmosis has taken place. Using more of the same concentrated Molar solutions, would have helped me to obtain more accurate results, therefore cutting out on the anomalies, this would provide a better line of best fit, as there would be more results, so I would have a better average. I think, we have left the experiment for 24 hours which is long enough for Osmosis to occur, so do not feel that this should be changed. Other extension tasks could be made with different plan tissues like apple. I could also take more results at the molarity levels, for example: 0.2, 0.25, 0.3... etc. The shape and size of the potato could be changed though this would make no difference to a result. This is because the variable would only change the rate of osmosis because of a different weight and size. The temperature may be changed, with varing temperatures instead of just room temperature. The test tubes containing the sucrose solutions and the chips could be placed in different water baths at different temperatures and left for 24 hours. I would expect that at the highest temperature osmosis would be the most. For at higher temperatures the solutions water molecules would diffuse faster and therefore equal the concentration faster. This is because the rate of diffusion is increased by heat to a certain point. Overall, I think this experiment has been quite a success, and I am pleased with my results. Mihir Desai A.M.F. ...read more.

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