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The firmness of a potato may be affected by its age. Also if it was stored in a salt and water solution over night for example its firmness could be affected by the concentration of salt contained in the water.

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Introduction

Biology - Coursework Planning The firmness of a potato may be affected by its age. Also if it was stored in a salt and water solution over night for example its firmness could be affected by the concentration of salt contained in the water. For my biology coursework I am planning to investigate how the size of a potato could be affected by being kept in different concentrations of salt and water. I will try to change this factor by adjusting the concentration of salt in five test tubes, which will contain identical pieces of potato. A potato is made up of plant cells. Each plant cell is made up of a cell wall, cell membrane, cytoplasm, nucleus and vacuole. The vacuole of a plant cell contains sap, which consists of water, sugar and salt. By placing pieces of potato in different concentrations of salt and water, the size will be affected by a process of diffusion. The method of diffusion that I expect to happen is called osmosis. This is when water moves from a dilute solution to a stronger solution. So if the concentration of salt inside the cell's vacuole is stronger than the surrounding solution that the potato has been placed in, water should then diffuse into the potato. Therefore causing it to expand. ...read more.

Middle

The first experiment done will be called "Set A" and the second will be called "Set B", to avoid any confusion. Results from Set A Chip No' ( % placed in ) Length at Start (cm) Weight at Start (g) Length at End (cm) Weight at End (g) Chip1 - 0% 2 2.2 2.2 2.5 Chip2 - 5% 2 2.3 2.1 1.6 Chip3 - 10% 2 2.2 2 1.7 Chip4 - 15% 2 2.2 2 1.8 Chip5 - 20% 2 2.1 1.9 1.7 Results from Set B Chip No' ( % placed in ) Length at Start (cm) Weight at Start (g) Length at End (cm) Weight at End (g) Chip6 - 0% 2 2.2 2.3 2.7 Chip7 - 5% 2 2.2 2 1.5 Chip8 - 10% 2 2.1 2 1.6 Chip 9 - 15% 2 2 1.9 1.7 Chip10-20% 2 2.1 1.8 1.8 Differences from Set A Chip No' Difference in Length (cm) Difference in Weight (g) Chip1 0.2 0.3 Chip2 0.1 -0.7 Chip3 0 -0.5 Chip4 0 -0.4 Chip5 -0.1 -0.4 Differences from Set B Chip No' Difference in Length (cm) Difference in Weight (g) Chip6 0.3 0.5 Chip7 0 -0.7 Chip8 0 -0.5 Chip9 -0.1 -0.3 Chip10 -0.2 -0.3 Analysis and Conclusion (Refer to appendix 2 and 3) The graph that illustrates any length decrease or increase shows that in both experiments, the potato chip became shorter as the concentration of salt became stronger. ...read more.

Conclusion

Therefore the potato chip does not lose as much weight as expected. In this experiment the length of the chips did not change four times, twice in Set A and twice in Set B, this happened even though the weight decreased. Here I am made to believe that the chips must have shortened in width and not length. Evaluation In my investigation I wasn't happy with the length results which I obtained after doing the experiment. They did not really relate to the results I had recorded about weight. For example - chip2, its weight decreased and its length increased. This is probably because I measured the length of the potato chips using a ruler and unlike where I weighed the chips using an electronic weighing scale, there was an opportunity for human error to occur. If I decided to take the time and repeat my experiment again I would make sure that the length measurements taken would be as accurate as possible. Also as I said earlier, the width could of increased or decreased in size so if I decided to repeat the experiment I would record width measurements also. The experiment proved my prediction to a certain degree; I was not expecting the weight loss to go up after a certain point. In my prediction I never really took the solution's saturation point into consideration. It only dawned on me after I had recorded my results as a graph. Ebonni Chabala 11R ...read more.

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