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The aim of this experiment is to investigate different concentrations of sucrose solutions and eventually determine the molarity of the cells inside the potato.

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Introduction

Peter Dobson 11 Teresa Investigation to determine if different concentrations of sucrose solutions affect osmosis in potato cells The aim of this experiment is to investigate different concentrations of sucrose solutions and eventually determine the molarity of the cells inside the potato. Osmosis is the process by which water molecules move from an area of low solute concentration to an area of high solute concentration through a semi-permeable membrane. From this experiment I also hope to be able to find the isotonic point, the point where the mass and the length have not changed from how they were at the start of the experiment. This will enable me to find out the molarity of the potato cells. Equipment list for this experiment: * Potatoes * Sucrose solutions * Distilled water * Scalpel * Ruler * Test tubes * Test tube rack * Pipettes * Square tile * Potato corer Once this equipment has been gathered, I will carefully cut 9 cylinders out of the same potato, because different potatoes may be slightly different. These will then be carefully measured and weighed to ensure that they are all the same size, which will make it easier for comparison after the experiment. They will all be cut to 30mm in length and will all weigh 2.0 grams. ...read more.

Middle

The new mass of each cylinder can be compared with its mass reading before being placed in the solution in the test tube. Also the cylinders will be measured to note its new length. This new length can then be compared with its original length of four centimeters and thus with this information compiled together, I will be able to analyze what has happened with the help of what I have learnt before on the topic of osmosis. From this table and the graph overleaf, it is obvious that with a less concentrated solution, the potato cylinder gains length. For example, when the potato cylinders are placed in distilled water, from four centimetres, they increase in length to 4.42 centimetres on average, an increase of 42 millimetres. This relies on the fact of osmosis; if a cell is placed in a less concentrated solution, then water must move into the cell so that the concentration gradient is eliminated. Since the potato cells inside the cylinder have a mixture of salts and sugars with water, it forms a weak solution. Even though it is weak, it is still more concentrated than the distilled water. In order for equalization to occur, some of the distilled water must move across the cell membrane of the potato cell and enter it. ...read more.

Conclusion

It also allows the potato cylinders to be submerged fully in their respective solutions for up to 24 hours so that enough time is given for the process of osmosis to occur. Nevertheless, there are several improvements that could be suggested in order to make the method even more reliable. The first way to improve my experiment would be to keep the temperature constant. If I were to repeat this experiment again, I would keep the test tubes containing the cylinders inside a stored area, where the temperature is kept constant always; this will prevent the chance of any change in the rate of osmosis and thus will prevent any inaccuracies in the mass and length readings. In order to prevent the cylinders from being irregular, I will use only those potato cylinders that are almost a perfect cylinder. In this case, the readings in mass and length would be more accurate. Another common error to overcome is that when using the measuring jar to confirm 30mL of solution to be used, I will make sure to take this reading at eye level so that I am actually using an exact volume of 30mL exactly. Also an error can be avoided when cutting the potato cylinders to an exact four centimeters; its length should be noted at eye level to confirm the length of the cylinder is four centimeters. And finally, in order to prevent the concentration of the potato cell from altering, I will use the same potato. ...read more.

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