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Osmosis in Potato Cells

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Osmosis in Potato Cells Aim: In this investigation I will be investigating the amount of osmosis in potato cells and whether osmosis and potato mass changes in different strengths of sugar solutions. I will do this by putting a constant amount of potato in solutions with steadily increasing sugar contents. Preliminary: I decided to under take a preliminary experiment to find out whether there are any problems or hitches that would have to be sorted out before the real experiment. For this preliminary experiment I took three Potato chips each made by a borer. My partners (Alex and Dan) and I made the chips 5cm in length with a diameter of 9mm and an average mass of 4.2 grams measured on a balance accurate to 2 decimal places. We then added each of the potato chips into a different solution in boiling tubes. The three solutions were 100% sugar solution with no distilled water, 50% water and 50% sugar solution, and finally 100% distilled water. We then left these Potato chips for 45 minutes and recorded are results in the table below: Solution Mass before Mass after Mass change No sugar 4.1g 5.5g +1.4g Weak sugar 4.2g 4.5g +0.3g Strong sugar 4.4g 3.2g -1.2g What we found out after the experiment was that the stronger the sugar solution the more mass the potato lost. ...read more.


Where as the chip in the 100% Molar solution will move the water molecules from inside it self into the solution to try and make the solution and chip have the same water particles making the Potato chip very flaccid. Shown below is the process of Osmosis: This is what is happening in the Potato experiment. The water is trying to balance out the solution so is moving from a low concentrate to a higher concentrate. This is different to diffusion because in diffusion the molecules move from a high concentrated area to a low concentrated area. My prediction of the change in mass is that the higher molar % in the solution the more negative mass change you will get however for the middle Molar strength solutions I believe that there will be little if no change in the mass and therefore will be a center mark for the rest of the results. A graph showing the average mass change should show the largest positive change for the 0.0 M then a steady decline to the biggest negative change in mass for the 1 M solution. Apparatus: 10ml measuring cylinder - to measure out exactly 10ml of each sugar solution 15 test tubes - what the experiments will be held and carried out in. ...read more.


My results could have been more accurate by using a balance that was accurate to more than two decimal places. This would be more accurate but possibly not necessary as two decimal places I believe are enough to give me a good result. More accurate results may have been achieved by being more precise with the measuring out of the solutions, whilst I measured as accurately as I could, with different equipment I may have been able to be more precise. I could have tried to be more accurate in the final stages of the experiment for example, I could not reliably measure how much water I dried off each potato chip before their mass was collected so this may have affected the results. Other things that may have varied include trying to keep the same mass of the chip at the start, the amount of time that I left the potatoes in the solution and the conditions that each of the solutions were left in. These adjustments may only be tiny changes but they may affect the final result. So to conclude I think that the experiment was a success but there are many areas that I could improve. If I did it again I know that I would expect to see a greater variety of results and graphs. ?? ?? ?? ?? *** Rob Shanley *** ***Biology Coursework*** ...read more.

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