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Factors affecting Osmosis in Potato tissue

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Factors affecting Osmosis in Potato tissue Introduction There are many forms of diffusion; one form is osmosis, which needs little energy to occur. Osmosis is the process when water diffuses across a selectively permeable membrane to an area of high solute concentration. This can also be said that it is the movement of water molecules, from a high concentration, to an area of low concentration of water. When there is a high concentration of water, it is also called 'high water potential.' The diagram below shows a simple idea of what is meant by the process of osmosis. The small black circles in the diagram represent the water molecules, the larger represent the solute. FIG1 When plant cells are surrounded by a dilute solution, they let water into the cell, and therefore become more turgid. As the diagram shows... FIG2 When a plant cell is placed in a solution with a high solute concentration, then the water will leave the cell and the cell will become shriveled and flaccid. FIG3 When a red blood cell is placed in a dilute solution, then it takes in water, but because it doesn't have strong cell walls like a plant cell, it will burst. FIG4 Planning What I have been asked to find out for this investigation, is the factors affecting, the process of osmosis in the tissue of a potato. The factor that I have been asked to investigate is, 'what affect does the concentration of the solution have on osmosis? ...read more.


It is almost certain that the mass will increase, as the potato is in a zero concentrated solution, so water will move into the chip. The results of the experiment were... Time/ min Original Mass/ g Mass after experiment/ g Mass gain/ loss/ g Percentage gain/ loss % 5 4.16 4.38 0.22 5.3 10 3.75 4.41 0.66 17.6 15 3.68 4.39 0.71 19.3 20 4.2 4.8 0.6 14.3 From my results I can see that the most efficient was the chip that was in the test tube for 15 minutes. However I think that it should have been the one that was in 20 minutes that had the highest percentage rise, as there was more time for osmosis to take place. This could have been down to measurement mistake on my behalf. I have decided to use 10 minutes as my time in my experiment. This is because it gave a significant result, and gives me enough time to do the experiment properly. I have also decided to stick to the potato chip being 8 x 0.5 x 0.5cm, and the volume of water in the test tube as 30ml, as both gave good results. Results Concentration of solute/ M Initial mass/ g Mass after 10 minutes/ g Mass gain/ loss g Percentage gain % Average Percentage gain % 0 3.75 4.41 0.66 17.6 11.8 0 5.36 5.68 0.32 6 0.25 3.59 3.62 0.03 0.8 0.5 0.25 4.32 4.33 0.01 0.2 0.5 3.7 3.55 -0.15 -4.1 -4.5 0.5 4.62 4.4 -0.22 -4.8 0.75 4.09 3.85 -0.24 -5.9 -5.3 0.75 4.34 4.17 -0.17 -4.6 1 3.93 3.59 -0.34 ...read more.


How I would make my experiment better, would be that when I took the chip out I would use my finger and wipe the surface, making sure that there wasn't too much solution on the outside affecting the mass. To make sure that there was as little evaporation as possible, I would do my experiment nearer to weighing machine and I would have a fan working next to my experiment, this would make the air around the chips as cool as possible. Also, the way I would remove my chip from the test tube would be that I would pour the content of the test tube into a sink, but catching the chip in my hand. This way I wouldn't put so much force on it. To extend my investigation, I could do the same experiment, but using different vegetables. Such as carrots, lettuce, leek etc. I would collect results in the same way I did for the potato. Also in the same way as I found the concentration of the solute in a potato cell (when it was isotonic), I would find out the concentration of other vegetables cells. Once I find out the concentrations, I could see if there is any connection on why they have certain concentrations. It could be for climate and environmental reasons that they need different strengths of solution. To see if this is true, I could do the experiment on vegetables that grow in a cold climate, and then test vegetables that grow in warm climate and see what (if any) differences there are. Conducting Paper Investigation Physics G.C.S.E Coursework William Davies 10 Keats ...read more.

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