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Investigation into factors that affect Osmosis in potatoes.

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Introduction

Investigation into factors that affect Osmosis in potatoes I will investigate how different concentrations of sucrose affect potato in terms of turgidity. The sucrose will be in varying concentrations compared to water. I hypothesise that the higher the concentration of sucrose around the potato, the more mass the potato will lose. I believe that this will happen as the potato will try to lose water to equalise the concentration of the sucrose compared to water, this is the process of osmosis. This happens through the pores on the selectively permeable membrane on the potato, which allows water through it but not sucrose. To measure the effect of osmosis with sucrose on potatoes, I will measure percentage change in both length and mass, using balances and measuring implements. I will measure weight to 2 decimal places, and length to the nearest millimetre. I will follow normal laboratory procedure, and will take special precautions when using scalpels and borers. I will cut the cylindrical pieces of potato to the same diameter which is 5mm, by using a cork borer and to the same length (4cm), by using a scalpel. I will put the piece of potato into a boiling tube, and I will put varying concentrations of sucrose in with it. I will put 10ml of sucrose with 0ml of water, then 8ml Sucrose and 2ml water, then 6ml sucrose with 4ml water, then 4ml sucrose with 6ml water, then 2ml sucrose with 8ml of water and 0ml sucrose with 10ml of water. ...read more.

Middle

- to cut the pieces out of a potato White tile - to prevent damage to the bench Boiling tube rack - to hold the boiling tubes Sucrose (1 molar) - for the solutions Distilled water - to vary the concentration of sucrose Bungs - to stop air getting in the boiling tubes 100cm3 Beaker - to keep the sucrose in Pipette - to transfer the sucrose to the boiling tubes Ruler - To measure pieces Scales - To weigh pieces Blotting paper - to take away surface water from pieces Obtaining Evidence I used the equipment listed in the plan, and it all worked properly. To measure the length, I just lined up the pieces against the ruler and measured them. I did the same thing with the set up of the experiment, where I measured a 4cm strip of potato and cut it with a scalpel. I believe that the results I have obtained are both reliable and accurate, as I carried out my plan correctly and exactly and repeated the experiment three times. I believe that I have taken enough observations, as I have three sets of data. I believe this is enough to enable me to observe correct trends in the data. I believe I have covered the whole range of data that I intended to collect - that is the change in length and mass. ...read more.

Conclusion

I believe that the experimental uncertainties are within acceptable limits. I can and have used scientific theory to support my results, and I believe that my evidence is sufficient to support my decision. I feel that three sets of data is enough to make a valid conclusion and I have proved this. I believe that it was a fair test, due to the fact that I repeated the experiment exactly each time. My results should be reliable and reproducible, as they follow the theory about osmosis. If I had to repeat the work, then I would not really change anything. I might leave some samples for longer time periods, to see what would happen. I would use the same equipment as it all worked as I wished it to, but I may use more accurate equipment - like scales to 3 decimal places. I would choose the same variables, but I might experiment with one more, maybe temperature. If I had more time to do the experiment then I would investigate all the variables, and would experiment with different sizes and types of potato. I would also take more readings for example 1/9, 3/7 and 5/5 concentrations of sucrose to water. These would make the results and conclusion more accurate and reliable. I would use additional evidence, by maybe using completely different techniques and equipment to see if those results are comparable to my own. ...read more.

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