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Osmosis in potato chips.

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Osmosis in potato chips Osmosis is by definition, the diffusion of water from a weaker, or more dilute solution, to a stronger solution (i.e. down the water concentration gradient) through a partially permeable membrane, and it is this principle which I want to study. My teacher has done the planning to me for investigating the effect of osmosis on potato chips. In order to observe any results, and draw a conclusion from them, I need to thoroughly research osmosis and it's effect on plant cells. Osmosis can occur in plant cells, and allows processes such as transpiration to occur. It also can change the structure of a cell, to a point where the cell can no longer function. Osmosis is the only way that water can diffuse in and out of a cell. When the solutions on either side of the partially permeable membrane are equal (in strength), or isotonic, the net movement of water is zero. As there is no difference between the solutions, no water needs to be moved in order to dilute, and osmosis does not occur. Prediction: In this experiment, I would expect the different concentrations to show fairly noticeable effects on the lengths of the potatoes, with the water diffusing into the potatoes at a high rate in the pure water solution, and therefore making their size bigger than at the start. As the solutions become stronger, I expect the rate of osmosis to decrease (and as a result, make the potatoes themselves comparatively smaller at the end). ...read more.


Osmosis has occurred, and water has diffused from the solution into the potato, in an effort to dilute the solution in the potato. This is because the solution is of a weaker concentration (more water molecules) than the solution inside the potato. This has caused the potatoes to become turgid, with the inner turgor pressure pushing the cell membranes up against the cell walls. This makes them stiffer and much like the stems of plants, which, use their turgid state to hold the plant up. This is different to the other four solutions. In these solutions the potatoes have become limp, decreasing in length, again due to water loss. Again, the only way that water can be gained or lost from a plant cell is by osmosis. However, instead of there being osmosis into the potatoes, the water is diffusing out of the potatoes. This is because the solution inside the potatoes is now of a weaker solution (more water molecules) than the solution in the petri dish, and as a result, the water in the potatoes' solutions has diffused through the partially permeable membranes of the potato cells, and into the outer solutions. As a result, the inner turgor pressure has reduced, a little in the second and third solution, but a progressively more in the fourth and fifth solution. I think this reduction in pressure has made the cells' membranes pull away from the cell's walls, as there is no turgor pressure, and the cell becomes plasmolysed, whereby the plant cannot expand and take in any more water. ...read more.


If the inquiry were to be repeated I don't think I had recommended a potato because it is too fiddly (an irregular shape) difficult to cut and there is too much room for error, but if it was possible with sufficient time and more careful planning and accuracy, sugar solution could be used instead of salt to see if this produced the same results as salt and verifying the hypothesis that osmosis will occur. If osmosis really does occur when water gradient is less than other, the trend should be evident with any substance soluble in solution. We could even change the type of potato to see if all potatoes behave the same during osmosis, providing we conduct the experiment correctly. Even better, a vegetable that is easy to cut such as a cucumber, something already cylindrical and repeat the investigation (mass not length) on that. At least the slice would lay flat say in a petri dish and maybe completely submerged (encouraging osmosis) producing a more accurate result. I also know that cucumbers have high water content so any change should be more apparent. However you propose to discover osmosis in potatoes there is always room for human error and under classroom conditions and limitations in time, (which we need more of) to complete our experiment to the standard of something substantial proving or disproving my hypothesis is very difficult. Secondary sources used: www.bbc.co.uk www.studentcentral.co.uk www.google.com www.oxfordresearch.com Advanced Level Biology GCSE Biology Key Science Muhammad Khasimullah GCSE Biology Coursework Osmosis Coursework ...read more.

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