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Potato chips and Osmosis

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Biology Coursework Potato chips and Osmosis What it's all about...: I am going to conduct an investigation to find out at which sugar concentration osmosis best takes place on a potato chip. Osmosis is defined as the net movement of water or any other solution with molecules from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a partially permeable membrane such as a cell wall, which lets smaller molecules such as water through but does not allow bigger molecules to pass through. The molecules will continue to diffuse until the area in which the molecules are found reaches a state of equilibrium, meaning that the molecules are randomly distributed throughout an object, with no area having a higher or lower concentration than any other. Membranes are very thin sheets of material which surround living cells. For example, thin cellophane is a membrane. They have tiny holes in them to allow small particles to get through. Particles like water molecules can get through easily; however, larger molecules such as starch cannot. If a membrane separates a strong and a week solution, the water molecules will pass through the membrane until each solution is of equal strength. ...read more.


This therefore means that the chip will increase in size when there is no concentration of sugar present in the solution (ie, distilled water). I reached this hypothesis as a result of my pilot experiment, because of the size of the molecules. The concentration of water molecules inside the potato chip cells will be higher than that in the surrounding solution, as it is a solid and the solution is a liquid. The most movement of water molecules will be form the potato chip into the solution. This is because they are going from an area of high concentration to an area of low concentration. The weight (mass) of the potato chip will decrease because of the vacuoles. Planned Method: A range of sucrose sugar solutions will be prepared with concentrations 0%, 1%, 2%, 5%, 10% and 20%. This will be done by adding varying amounts of distilled water to varying amounts of sucrose solution. Sections of potato will be cut using a standard kitchen knife and will be weighed using a pair of scales. This part of the preparation must be done very accurately as a change in the surface area may allow more or less osmosis to occur. ...read more.


The poor results were due to two things. Firstly, the potato chips were cut from different potatoes due to human error. These caused the most change as the two potatoes could not have been identical and had different physical and biological properties. The other thing that affected the results were that the samples were put into the fridge overnight, slowing down the process of osmosis drastically. My prediction was proved to be wrong apart from in the 20% solution. This was down to the pilot experiment being conducted differently to the real experiment. Had this been done properly, my prediction would have matched the results. My method showed how the experiment should be done, and I have full confidence that should I repeat the test; my method will make the results come out better. The only result that didn't seem to fit in with the pattern was the chip in 20% sucrose solution. I have already explained the reasons, and in future tests I will make sure not to make those mistakes again. Overall, the experiment wasn't what I expected, however, I learned a lot of things regarding osmosis and diffusion, and I have better ideas of how to conduct the experiment in the future should I wish to repeat it. ?? ?? ?? ?? Khalid Edah-Tally Biology Coursework 2005 ...read more.

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