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Experiment to investigate the effects of various sucrose solutions on potato.

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Introduction

Experiment to investigate the effects of various sucrose solutions on potato. Osmosis is defined as the net movement of water or any other solutions molecules from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a semi-permeable membrane such as a cell concentration i.e. in the solution; to a low concentration i.e. in the potato piece. Therefore, the potato pieces in a higher water concentration (low sucrose) will gain more mass through osmosis than those pieces in a higher sucrose concentration. however, at a point, in the concentration change, I expect the potato to actually lose mass. This is due to the fact that as the concentration of sucrose in the solution increases, it will reach a point where the potato and the solution are isotonic (the concentration of sucrose in the solution equals that of the concentration inside the potato) any higher concentration of sucrose in the solution thereafter will result in osmosis occurring in the opposite direction; i.e. water molecules will be moving from a higher concentration inside the potato, to a lower concentration in the solution itself. ...read more.

Middle

4. The volume of the solution that the potato chips are kept in must be fair. They must be totally covered in the solution, and the amount of solution will be kept the same because all the potato chips are the same size. 5. I am also going to use the same balance to weigh my potato chips. This is because the measurements may slightly vary between scales. Method A range of sucrose sugar solutions will be prepared with concentrations of 0% sucrose (water), 5% sucrose, 10%, 15% and 20%. Sections of potato will be cut using an apple corer, and a sharp knife (see safety), care taken to ensure the slices are as equal as humanly possible, as a change in the surface area may allow more or less osmosis to occur. The mass of each chip will also be measured and recorded. Five chips will be placed in each petri dish each time so that and average may be taken from each dish and thus, solution. 20 ml of each concentration of sugar solution will be added to each petri dish (preliminary experiment showed this was the optimum amount) ...read more.

Conclusion

This would also have allowed me to find the isotonic point far more accurately as the one that I estimated is very approximate. The cutting of the potatoes was the most difficult part of the experiment as, although I was recording my results by mass, it could well have affected the surface area and so the overall rate of osmosis. If I were to repeat the experiment I would have possibly found a machine to cut the potato, as it would ensure that all potatoes would be the same weight and dimensions. I encountered no striking anomalies, however, I did find that some values were not as close to best fit than others. This may have been caused by human error, e.g. when the potato chips were removed from the test tubes and dried I may well have dried some potatoes more thoroughly than others and so some would have more excess water, which would add to the mass. If the experiment was repeated I could find another way to dry the potatoes that would ensure that all were dried in the same way for the same time. However with all this said I think that the experiment was truly successful and I was very pleased with the complete comparison of my results with my initial prediction. ...read more.

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