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Investigate the effects of different concentrations of sugar solutions on the weight (mass) of potato pieces.

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Introduction

Biology Coursework - Chloe McGeown 11D An Investigation into the Effects of Sugar Solutions on the Mass of Potato Cells. Aim: To investigate the effects of different concentrations of sugar solutions on the weight (mass) of potato pieces. Prediction: I predict that the weight of the potato will rise when soaked in the weaker concentrations of sugar. This is because during the process of osmosis the water molecules will pass from the weaker solution across a semi-permeable membrane into the potato. As the sugar concentration in the prepared solutions rises there will be a point where the weight of the potato will begin to fall. This will be because osmosis will cause water molecules in the stronger solution to move across the semi-permeable membrane out of the potato and into the prepared sugar solution. I also predict that at a point there will be a time where water is moving neither in nor out of the potato. This will be because the sugar concentration of the prepared solution and the sugar concentration of the potato are the same. ...read more.

Middle

This difference was then changed into a percentage and shown as a positive or a negative depending on whether the potato had gained or lost weight. The whole experiment was repeated and the results were recorded separately (set A and set B). Results: Set A Concentration Before After Difference % Change 0% 1.47g 1.50g +0.03 +2.04% 5% 1.49 1.42g -0.07 -4.70% 10% 1.59 1.38g -0.21 -13.20% 15% 1.33g 0.94g -0.39 -29.32% 20% 1.42g 0.94g -0.47 -33.10% 25% 1.28g 0.81g -0.47 36.72% Set B Concentration Before After Difference %Change 0% 1.16g 1.26g +0.10 +8.62% 5% 1.40g 148g +0.08 +5.71% 10% 1.35 1.36g +0.01 +0.74% 15% 1.39g 1.18g -0.21 -15.17% 20% 1.17g 0.87g -0.30 -25.67% 25% 1.39 1.01g -0.36 -26.28% Both sets of results were plotted onto a graph and the lines of best fit drawn in. Conclusion: Both sets of results support my predictions and when left in the weaker solutions, the potato pieces took in water by the process of osmosis. As the concentrations of the prepared solutions increased, the potato pieces began to lose water. This shows that in both experiments osmosis did take place. ...read more.

Conclusion

Other factors remained constant. The temperature in the room and the prepared solutions were the same for both experiments and so should not have affected the results. If I were to repeat these experiments again, I would make sure that I used potato pieces that all came from the same potato. This would make it more likely that the concentrations of solutions in all of the potato pieces were the same to begin with. This should make both sets of results closer and the point at which equilibrium is reached similar. I would also continue the experiment further to see at what concentration of prepared solution the potato pieces actually stopped losing water. The results for set B show that weight loss had dramatically slowed down for the 25% prepared sugar solution. Set A shows that even by 25% prepared sugar solution the potato was still losing quite a lot of water and osmosis was still going on. Finally, I feel that this experiment was successful and that the results back up my predictions. There were no real anomolies in either set of results and the process of osmosis worked as I had expected. ...read more.

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