Wednesday, September 18, 2019
Effect of Concentration on Osmosis Essay -- GCSE Biology Osmosis Cours
Effect of Concentration on Osmosis Aim To find out how the concentration of sucrose solution affects the mass of the potato chip left in the solution for one day. Prediction I predict that when the sucrose concentration is low the potato chip will gain mass. This is because there will be a higher sucrose concentration in the potato chip so water will go into the potato from the solution. I predict that when there is a high concentration of sucrose the potato will lose mass. This is because there is a higher concentration of sucrose solution in the solution compared to that in the potato chip so water from the potato will go into the solution to even it out. Osmosis is "the movement of a solvent through a selectively permeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane" Osmosis is the movement of water from high water concentration to lower water concentration through a selectively permeable membrane. Selectively permeable membranesare very thin layers of material (cell membranes are selectively-permeable), which allow some molecules to pass through them but prevent other molecules from passing through. Cell membranes will allow small molecules like Oxygen, water, Carbon Dioxide, Ammonia, Glucose, amino-acids, etc. to pass through. Cell membranes will not allow larger molecules like Sucrose, Starch, protein, etc. to pass through. In my experiment I will have a test tube with a potato chip in. The outside wall of the potato chip is selectively permeable so it lets water pass through it but not bigger molecules such as sucrose. In the test tubes I will put different concentrations of sucrose solution. When the concentration of the solution is lower than that in the potato, water will pass through the selectively permeable wall into the potato. Potato cells Sucrose solution The mass of the potato chip increases Sucrose molecule Water molecule When the sucrose solution is stronger outside if the potato chip water will move out from the potato chip into the solution. When the concentration is the same on both sides of the selectively permeable wall nothing passes through it and the mass will stay the same. Plan Apparatus Five test tubes Labels Ruler Scales Tissue... ...hips in each test tube. This would make it more accurate as when I had two in a test tube if one of them was a long way out it made the graph not follow the line well when I plotted the averages. There was one anomalous result at 0.5 mol. I think this was because we patted them dry when we got them out of the test tubes as we did not want to weigh there water on the outside of the potato but I think that we may not have dried them all equally so this anomalous result may have been due to it having water left on the outside of it. Also the potato itself was not from the same part of the potato and was not exactly the same size, although I did try to cut them to 36mm each. I could also try the same experiment but with different volumes of cell tissues and see if the percentage change differed with a bigger and smaller surface area. I could now investigate the smaller range near to 0.25 to see the sucrose concentration equivalent to the potato. Finally, I could extend the experiment to a more exact level by looking at the potato cylinders under a microscope, then I would be able to see the cells in greater detail and draw some more observational results.