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Biology Coursework No.1- Osmosis

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Introduction

Biology Coursework No.1- Osmosis Aim The aim is to investigate the effect of changing concentrations of glucose mixture in water in potato chips using osmosis. Prediction * In the pure water (0% glucose) solution, I believe that the potato chip's mass would increase. * In the 2% glucose solution, I believe that it will also gain weight, but not as much compared to the 0% glucose solution. * In the 4% glucose solution, I too believe that it will gain weight, but again, not as much as the 0% or 2% glucose solution. * In the 6% glucose solution, I believe that the potato chip will remain the same weight. * However, in the 8% solution, I believe that the potato chip will loose weight. * Similarly, in the 10% solution, I too believe that the potato chip will loose weight * . However it will be more compared to the 8% solution. I think this will happen because I am guessing that the isotonic point( see above) for the potato chip is somewhere between 4% and 8 %.The potato chip in 4% will have a lower water potential than the water around it and will therefore gain water due to osmosis. ...read more.

Middle

Again, water crosses the cell membrane in both directions, but this time more water leaves the cell than enters it. Therefore the cell will shrink. Plant cells Plant cells always have a strong cell wall surrounding them. When they take up water by osmosis they start to swell, but the cell wall prevents them from bursting. Plant cells become "turgid" when they are put in dilute solutions. Turgid means swollen and hard. The pressure inside the cell rises, eventually the internal pressure of the cell is so high that no more water can enter the cell. Turgidity is very important to plants because this is what make the green parts of the plant "stand up" into the sunlight. Animal cells When animal cells are placed in sugar solutions things may be rather different because animal cells do not have cell walls. In very dilute solutions, animal cells swell up and burst: they do not become turgid because there is no cell wall to support the cell membrane. In concentrated solutions, water is sucked out of the cell by osmosis and the cell shrinks. Previous Experiment: Cut 2 pieces of visking tubing to x cm long. Tie the ends off. Fill "cell A" with glucose solution and "Cell B" with water Weigh "cell A" and "cell B" Put "Cell A" into a beaker of water and "Cell B" into a beaker of glucose solution. ...read more.

Conclusion

3 0 % glucose solution Before: After: 0.85 g 0.9 g Before: After: 1.12 g 1.16 g Before: After: 0.85 g 0.9 g 2 % glucose solution Before: After: 0.89 g 0.93 g Before: After: 0.92 g 0.96 g Before: After: 1.00 g 1.04 g 4 % glucose solution Before: After: 1.12 g 1.15 g Before: After: 0.85 g 0.89 g Before: After: 1.01 g 1.025 g 6 % glucose solution Before: After: 0.85 g 0.84 g Before: After: 1.18 g 1.16 g Before: After: 1.12 g 1.14 g 8 % glucose solution Before: After: 1.00 g 0.99 g Before: After: 0.96 g 0.94 g Before: After: 1.05 g 1.03 g 10 % glucose solution Before: After: 1.02 g 0.9 g Before: After: 1.12 g 0.7 g Before: After: 0.9 g 0.8 g Averages Glucose solution increase of decrease of 0% 0.043g 2% 0.04g 4% 0.0241g 6% 0.01 8% 0.013 10% 0.03 The following reasons, that the point for 2 % of glucose solution is distanciated from the line of best fit is that maybe the potato chips were: * Taken out too late * The weighing scale wasn't functioning * There might not of been a 2 % glucose solution, due to human error * The amount of water in the beaker wasn't the same ( see Fair Test) * * * * ?? ?? ?? ?? Benedikt von Lindeiner- 10 R - 1 - Biology Coursework #1- Osmosis ...read more.

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