Sunday, August 4, 2019
Finding out the affect of different concentrations of sucrose solution
Finding out the affect of different concentrations of sucrose solution on the mass of potato chips Introduction The aim of this investigation is to see when osmosis occurs in potato cells and whether anything happens to them when they are put in different concentrations of sucrose solution. I have to apply my background knowledge to devise an experiment which will tell me whether if different concentrations of water molecules in a solution will affect the mass of plant cell when they are put into it. Background knowledge Osmosis is like diffusion but only of water molecules and it only happens when there are different concentrations of water molecules on either side of a selectively permeable membrane. The selectively permeable membrane "gaps" are only small enough to let water molecules pass through and not big molecules such as sucrose molecules. Water molecules from each side of the membrane always pass to the other side. When one side of the selectively permeable membrane has a higher concentration of water molecules than the other, more water molecules from the side containing a higher concentration of water molecules will pass through to the side with a lower concentration of water molecules. Less water molecules from the side with a lower water molecule concentration will pass to the other side because there are less of them. If the concentration of water molecules on either side of the selectively membrane is the same then the net flow of water in either direction will be the same. This results in no net flow of water-osmosis. An example of osmosis happening in a plant cell is when a potato chip is put into distilled water. The cell membrane of the potato cells is the selectively permeable membrane between the concentration of water molecules inside the potato cells and the distilled water that is outside of the potato cells. As the concentration of water molecules is of a higher concentration in the distilled water than inside the potato, there are more water molecules going through the potato membrane into the cell than water molecules from the inside of the potato going through to the other side. This is because there are more water molecules in the distilled water. Therefore the net flow of water by osmosis is into the potato cells. As more water molecules pass into the potato cells, the va... ...Maybe next time I could roll each potato chip down the paper towel once and blot the ends of them two times on the paper towel. To prove that my prediction is correct in any osmosis experiment, I could do another experiment, which shows osmosis happening and why it happens-different concentrations between a selectively permeable membrane. The experiment is shown below: Apparatus * 20cm in length visking tubing. * 20cm3 water * 10cm3 plastic syringe * testing tube Method Tie a knot at the end of 20cm length visking tube that has been soaked in water. Put 3cm3 of strong sugar solution in the plastic syringe and use that to partly fill the visking tube-it should be floppy. Place the visking tubing into a test tube containing water 20cm3 . Leave the visking tubing in the test tube for about 30-45 minutes. You should record your observations of the visking tubing before it was put into the test tube of water and after it had been left in the water. Look for any changes in how it looks and feels. Is it turgid or flaccid? References Collins GCSE total revision Science by Mike Smith and Chris Sunley GCSE Biology second edition by D.G. Mackean
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