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Osmosis is the diffusion of a solvent from a less concentrated solution into a more concentrated solution through a semi-permeable membrane, permeable to the solvent but not to the solute.

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Introduction

Christian MacNamara 11MC BIOLOGY - Science Investigation: Osmosis PLANNING: Scientific Knowledge Osmosis is the diffusion of a solvent from a less concentrated solution into a more concentrated solution through a semi-permeable membrane, permeable to the solvent but not to the solute. (The Oxford Popular English Dictionary, reprinted 2000, Oxford University Press.) Diffusion is the movement of particles from a high concentration to a low concentration until they are spread out evenly. (Biology Exercise Book 1, 14/09/01.) Diffusion consists of the movement of large and small molecules, and in the case of Osmosis, the small particles are water (H2O) and the large particles are sugar (sucrose). The processes of Osmosis and Diffusion will be occurring in this experiment when the water in the potato diffuses from the area of high concentration (the potato) to the area of low concentration (the solution). Water (H20): Water is chemically formulated from 2 parts Hydrogen (H2) and 1 part Oxygen (O) Sucrose (C12H22O11): is a sweet crystalline dextrorotatory disaccharide sugar that occurs naturally in most plants and is obtained commercially especially from sugarcane or sugar beets (Encyclopaedia Britannica online dictionary.) Sucrose is used in the solution for this experiment. Plasmolysis: is the shrinking of the cytoplasm away from the wall of a living cell due to outward osmotic flow of water (Encyclopaedia Britannica online dictionary.) The process of Plasmolysis will occur when the water diffuses from the potato to the sucrose solution due to Osmosis. ...read more.

Middle

This goes the same for all the other groups whom we will be sharing our results with. Measuring Apparatus: - A ruler was used to accurately measure the length of the potato cylinders to the nearest mm. - Accurate weighing scales (2d.p.) were used to measure the mass of the potato cylinders both before and after the experiment. OBTAINING EVIDENCE: Results Table of Results: (anomalies are shown in red) Experiment 1 Sugar conc.(%) Mass Before (g) Av. Mass Before (g) Mass After (g) Av. Mass After (g) % Change in Mass 0 0.86, 0.84, 0.84 0.85 0.76, 0.83, 0.76 0.78 8.23 2 0.81, 0.86, 0.81 0.83 0.62, 0.66, 0.62 0.63 24.09 4 0.90, 0.89, 0.85 0.88 0.82, 0.88, 0.89 0.86 2.27 6 0.91, 0.92, 0.95 0.93 0.80, 0.74, 0.81 0.78 16.13 8 0.92, 0.96, 0.94 0.94 0.92, 0.88, 0.82 0.88 6.38 10 0.95, 0.93, 0.93 0.94 0.92, 0.92, 0.89 0.91 3.19 Experiment 2 Sugar conc.(%) Mass Before (g) Av. Mass Before (g) Mass After (g) Av. Mass After (g) % Change in Mass 0 1.10, 1.00, 1.30 1.13 1.52, 1.52, 1.59 1.54 36.28 2 1.10, 1.30, 1.30 1.23 1.41, 1.38, 1.21 1.33 8.13 4 1.30, 1.20, 1.20 1.23 1.21, 1.23, 1.18 1.2O 2.44 6 1.10, 1.20, 1.20 1.16 1.01, 1.08, 1.21 1.1O 5.17 8 1.20, 1.30, 1.20 1.23 0.92, 0.99, 1.00 0.97 21.14 10 1.10, 1.10, 1.20 1.12 0.92, 0.90, 0.91 0.91 18.75 ANALYSING EVIDENCE AND DRAWING CONCLUSIONS: On the next page is a ...read more.

Conclusion

This experiment, instead of measuring a change in mass of the potato, a change in length of the potato could instead be measured. This would require a different method and equipment list. Weighing scales would not be required, as the mass is not being measured. Also, the results would be in an entirely different form and the graphs would produce different patterns and curves. Essentially the experiment would be much the same, with the same control, fair tests and safety, but it may produce a more accurate set of results to show the affects of Osmosis, Diffusion and Plasmolysis on a potato. I am not sure of my results, they are not what I expected to be and I certainly would not bet on them being correct. This is mainly because of the peculiar set of results shown on the second graph. My results cannot lead to a confident conclusion as they are inaccurate and of a poor quality. The data was reasonably accurate to some extent, considering that any number of the mistakes mentioned above may have been the cause of anomalies and inaccuracies in the results. The data also shows patterns of some sort, meaning that the experiment was not a complete failure, and that some conclusion can be drawn for this individual experiment, even though a general conclusion for Osmosis in general is impossible to make out from these results alone. ...read more.

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