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What Factors Affect Osmosis in Potato Cylinders?

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Introduction

. What Factors Affect Osmosis in Potato Cylinders? The aim of this experiment is to investigate the volume of sucrose solution and the weight and volume of other variables which affect osmosis in potato cylinders. In this experiment I will weigh and blot rings of potato and test them in different concentrations of sucrose solution. I hope to find sufficient results as to investigate this. In this experiment I will be investigating, and putting to test, the theory of osmosis. The scientific theory of osmosis is the diffusion of water through a selectively permeable membrane into a more concentrated solution of sucrose. Because the more concentrated solution contains a lower concentration of water molecules, the water flows by diffusion to dilute it until concentrations of solvent are equal on both sides of the membrane. In simple terms, it may also be thought of as the passage of water molecules from a low solution to a high one, across a selectively permeable membrane. (This is shown in the diagram below). Sugar solution Distilled water Sugar molecule water molecule Low High Water Water Potential Potential Selectively permeable membrane Another experiment, published by the author B.S Becket in "Biology-a modern introduction", gives a clear understanding of osmosis. ...read more.

Middle

After the rings are cut I weigh each of the 3 potato rings on the weighing scales and write the weights of the rings into my table. I will then put those pieces onto a 6cm long piece of copper wire. They will be placed into a test tube filled with 20cm cubed of sucrose solution. I will place this on the rack, and leave it for 24 hours. After 24 hours, the rings will be weighed again. I will repeat this 6 more times with different concentrations of sucrose solution to see how the weight of the potato rings are affected. (See below for step by step instructions). 1). Use a cork borer to bore a tube of potato out of the potato. 2).Using the scalpel, cut the potato tube into three equal size rings. 3). Using weighing scales, weigh each separate ring of potato and record the weight into the table, (make more than one copy in case the original goes missing). 4). Put the potato rings on a 6cm long piece of copper wire, leaving space between each one. 5). Put the wire with the potato rings on it in a test tube filled with 20cm( of the first concentration of sucrose solution. ...read more.

Conclusion

The second ring was 0.43g heavier than the other two potato rings in the same test tube. The fact that it weighed more before meant that ultimately although it gained exactly the same weight as the other two, it's final weight was still larger. I had to change it's original weight so that my average would make sense. This tells me that the weight of the potato ring does not directly affect the osmosis in the potato ring. This confirms my prediction earlier that it is the concentration of the sucrose solution not the size or weight of the potato ring that affects osmosis. Overall my results seemed accurate enough. They backed up and developed my understanding of osmosis, and seemed to fit in with my theory and scientific knowledge. I could of perhaps taken more time over the cutting of the potato cylinders into rings, and measured my sucrose solution as accurately as I could manage. Although I do not think this would have affected my experiment directly, I t would have made my results clearer and easier to interpret. Of course I could have repeated my experiment for more accurate results, but this was just not possible . I believe I have successfully investigated all the factors I intended to. ?? ?? ?? ?? Thomas Godwin-Coursework ...read more.

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