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To investigate the effects of osmosis, in a potato, whilst in glucose and water.

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Introduction

To investigate the effects of osmosis, in a potato, whilst in glucose and water. Aim I am investigating the effects of osmosis in a potato whilst in glucose and water. Prediction I predict that the potato will expand more in the glucose solution than in the water. I think this because osmosis will take place. Osmosis is where the membrane only allows certain molecules through. This is because the membrane is selectively permeable. Scientific Knowledge Osmosis is the diffusion of water or other solvents through a semi permeable membrane, from where it is in a high concentration to an area of low concentration. Turgor is the pressure exerted by fluid in a cell that presses the cell membrane against the cell wall. Turgor is what makes living plant tissue rigid. Loss of Turgor, resulting from the loss of water from plant cells, causes flowers and leaves to wilt. Turgor plays a key role in the opening and closing of stomata in leaves. Diffusion is the process by which there is a net flow of matter from a region of high concentration to one of low concentration. ...read more.

Middle

Safety It was not necessary to take any safety precautions, as there wasn't any thing dangerously in the experiment. Fairness So as to make this experiment fair we were very precise when measuring the amount of water and glucose. We also made sure that the five pieces of potato were the same length. As well as this we removed the pieces of potato exactly on time. Variable used The variable that we used was the amount of glucose and water that was used in each test tube. Affecting variables The possible variables were the: Temperature, Size of potato, Length of Time which the potato, was left in the solution, Amount of glucose and water in each test tube. Measurement We did two trials for the experiment and we did two ranges. The piece of potato was three centre metres each time and we used fifteen millilitres of solution. Results Time (minutes) Test tube 1. (15mm glucose) Test tube 2. (5mm water, 10 glucose) Test tube 3. (7.5mm water, 7.5 glucose) Test tube 4. (10mm water, 5mm glucose) ...read more.

Conclusion

(10mm water, 5mm glucose) Test tube 5. (15mm water) 5 3.3 3.2 3.15 3.0 2.9 10 3.3 3.2 3.1 3.175 3.1 My prediction is supported by the results as the slices of potato increased in size when they were placed in the mainly glucose solution more than when they were placed in the mainly water solutions in fact the pieces of potato shrunk in the pure water. The glucose obviously induces osmosis whereas water doesn't. Evaluation This experiment is not particularly accurate as it was quite hard to remove the potato exactly on time therefore some samples spent more time in the solutions than others. This could well explain why there were so many anomalies. In order to improve this experiment I think that we would have to find an easier method for removing the pieces of potato, so that we could get them out on time. There were anomalies in: The first attempt, test tube 3 at ten minutes (3.2) The second attempt, test tube 4 at five minutes (3.25) The second attempt, test tube 5 at five minutes (3.1) I think that if I were going to repeat this experiment then I would continue taking readings up to twenty minutes. As well as this I would run four experiments instead of only two. ...read more.

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