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The aim of this coursework is to investigate how different concentrations of sugar solutions affect potato tissue.

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Introduction

BIOLOGY COURSEWORK Aim: The aim of this coursework is to investigate how different concentrations of sugar solutions affect potato tissue. The results obtained will tell me if the mass of the potato chips will change if placed in a variety of sugar solution concentrations for a given time. Apparatus: * Boiling tubes * 'Potato Chipper' * Potatoes * Water * A 1molar sugar solution * Ruler * Test tube rack * Paper towels * Weighing scales * Scalpel * Safety mat * Stop Clock Method: 1. Using the potato chipper cut 6 potato chips. 2. On the safety mat, cut each chip into cylinder shapes, aiming to make each chip as close to the same size as possible. Use the ruler to measure 1.5cm and cut each potato chip to that size. 3. Measure and record the mass of each potato chip. 4. Prepare 6 test tubes containing 30cm of the following concentrations of sugar solution each: 0.0M, 0.2M, 0.4M, 0.6M, 0.8M and 1.0M. 5. Place the potato chips in the boiling tubes and start the stop-clock. 6. Leave the apparatus for 1 hour. 7. Remove the potato chips from the solution after the 1 hour. 8. Dab the chips with a paper towel to remove excess water. 9. Measure and record the mass of the chips. Diagram: Variables I am investigating the effect that sugar solution concentration has on the potato chips so therefore to make the test as fair as possible, all other variables will remain constant: * Solution volume: Amount of solution used - Always 30 ml * Time/Duration: Time potato chips are submerged in sugar solution - Always 1 hour. ...read more.

Middle

Mass after (g) Mass change (g) Percentage change 2.65 2.65 0 0 2.66 2.63 -0.03 -1.13 0.15 Mass before (g) Mass after (g) Mass change (g) Percentage change 2.73 2.67 -0.06 -2.2 2.44 2.38 -0.06 -2.5 Results of both preliminary and final experiments in average form: Sucrose Level Mass before (g) Mass after (g) Mass change (g) Percentage change 0 2.42 2.73 0.31 12.8 0.05 2.54 2.76 0.22 8.7 0.075 2.65 2.85 0.2 7.8 0.1 2.57 2.73 0.16 6.4 0.125 2.66 2.64 -0.02 -1.13 0.15 2.59 2.53 -0.06 -4.7 Conclusion Based on my results I can reach a conclusion to this experiment. There is a definite link between the concentrations of sugar solutions and the effect on potato tissue. As the sugar solution concentration increases, the mass of potato chips decreases As the sugar solution concentration decreases, the mass of potato chips increases This is due to the Osmosis theory Osmosis is the movement of water molecules from a high water potential to a low water potential across a semi-permeable membrane Diagram of Osmosis Sugar molecules pass through pores Partially permeable membrane Water molecules Fewer water molecules go in this direction More free water molecules go in this direction Hydrated sugar molecule High concentration of free water molecules Low concentration of free water molecules Turgor Pressure in Plant Cell Movement of Water surrounding cell water High water potential cell wall Cytoplasm Cell membrane Vacuole Low When a potato chip is placed in water, the mass of the chip will increase. ...read more.

Conclusion

> Some chips came from different potatoes. I think that this point is quite minor. The different potatoes used may have had an influence giving inaccurate results. This problem could not have been avoided because only a limited number of potato chips can be cut from a single potato. One potato may have had a disease causing bizarre results to be taken. I do not think that this happened though. When I studied my graph, I noticed that the result for 1.0M might be anomalous. This unexpected result could have occurred due to many reasons, all of which are stated above. Some of the individual results shown on the tables on the third page were slightly anomalous but these were made normal by creating an average result. This means that my results were reliable - I did each experiment three times and then made an average. I did not record any measurements that were not following the theory of the concentration of sugar versus the mass change of the potato chips i.e. whenever the concentration of sugar solution was increasing, the mass percentage loss was always increasing. Whenever the concentration of sugar solution was decreasing, the mass percentage loss was always decreasing. There were no anomalous results in that sense. I cannot find any other points to comment on with unexpected results. If given time I would like to investigate how the period of time the chip were submerged in the sugar solutions effect the potato cells. Osmosis may have continued further in the cells after the 30 minutes that I left the chips for. This would be interesting to investigate. ****** ...read more.

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