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The Effect Of Concentration On Osmosis In Plant Cells

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Introduction

Eva Elks 11M Biology Investigation: The Effect Of Concentration On Osmosis In Plant Cells Hypothesis: The following factors all effect the rate of osmosis: * Surface area of the tuber * Concentration of sucrose solution * Amount of sucrose solution * Temperature * Time tubers are left in solution -The surface area of the potato tuber will effect the rate of osmosis because The more the surface area, the more osmosis will occur because more water can diffuse because there will be more area for it to pass through. I will control the surface area by making all my tubers weigh the same. This should ensure that they have roughly the same surface area. -The amount of sucrose solution will effect the rate of osmosis because there more solution there is, the more water there will be to pass through e.g. If the solution does not immerse the tuber, less osmosis will occur. -The temperature will effect the rate of osmosis because the particles will move faster in a higher temperature so more will pass through. -The time the tubers are left in the solution will effect the total amount of osmosis because the longer the tubers are left in the solution the more time the reaction has to occur, and therefore the greater the tubers change in weight. ...read more.

Middle

I will lift the tubers on and off the scale using the tweezers to make sure they are not contaminated 2. I will label my test tubes A, B, C etc so I can recognise them. 3. I will mix up my solutions before starting to put the tubers in, so I can put them all in at the same time. This will ensure they are all left in for the same amount of time. I will create my solutions by diluting the 1 Molar solution with the appropriate amount of distilled water. For example, when creating a 0.5 Molar solution we would mix 10ml of distilled water with 10ml of 1 Molar sucrose solution. 4. I will then place my tubers in 20ml of sucrose solution, ranging from 0M (pure water) to 1M (0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 and 1M) and leave them for 20 minutes. This is enough time for osmosis to occur. I will again move the tubers around using tweezers. 5. After 20 minutes I will remove the tubers from their solutions. I will remove any excess solution from them with blotting paper before re-weighing them and recording my results. ...read more.

Conclusion

I would also have liked to have redone all my experiments, leaving the tubers in the solution for 30 minutes, rather than 20 and takes 4 results each time. I feel this would have given me better results, as the tubers would have had more time to diffuse, and possibly allow me to find out the saturation point of the chips, and I would have better averages with the higher number of results. Again, it was not possible to do this because of time restrictions. The cutting of the potatoes was the most difficult part of the experiment as although I was recording my results by mass, it could well have affected the surface area and so the overall rate of osmosis. I was also unable to record the length of my tubers at the thickness varied, and they were not perfect tubes, but had edges missing. If I were to repeat the experiment I would have liked to find a more accurate way of cutting the tubers, possibly using a machine. I would also have liked to find a more accurate way of creating the different strengths of sucrose solution because bubbles in the syringes could have changed the strength of my solutions. The syringes used often had air bubbles and this could have affected the solution strength and therefore my results. ...read more.

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