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GCSE Osmosis Coursework My aim for this investigation is to study the effect of different strength of sugar solutions have on potato cells.

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Introduction

Christina Robinson GCSE Osmosis Coursework My aim for this investigation is to study the effect of different strength of sugar solutions have on potato cells. Science Theory Of Osmosis Osmosis is a type of diffusion. It is the passive movement of water particles from a region of high concentration to a region of low concentration across a partially permeable membrane. Once the water molecules on both sides even out it is called dynamic equilibrium GCSE Osmosis Coursework Preliminary Investigation For this part of the investigation my aim is to determine which strength sugar solution has the biggest effect on potato cells. I want to find out how the sugar solutions change the potatoes weight and length and which one is more accurate way to find the answers we are looking for. I predict, between the two sugar solutions, 0.25 molar will have the greatest change within the results. Safety Precautions To stay safe always wear goggles, tie long hair back, tuck stools under desks and remove anything from desks. Factors I will be controlling the amount of sugar solutions, length and weight of the potatoes. I am doing this so the result can be as accurate as possible. Method For investigation 1) Cut all potatoes to 4.8cm using a scalpel and borer 2) Weigh potatoes using scales, fill in data on table 3) Mark the potatoes 'A,B,C' with a marker pen 4) Pour 30cm3 of 1.25 molar sugar solutions into one test tube and 0 molar sugar solutions into the other test tube using measuring cylinders. 5) Place 3 potato tubs in each solution 6) Leave them for 20 minuets timed using a stop watch 7) Take potatoes out of tubes using a sieve 8) blot potatoes dry with paper towels 9) Weigh and measure the potatoes using scales and a ruler 10) Record findings on the results table Apparatus 7 x test tube 3 x beakers Scalpels Borer White cutting tile Measuring cylinder Stop watch Sieve Goggles Sugar solutions 21 x potato ...read more.

Middle

For the main investigation, I am going to use all 7 of the sugar solutions at levels 0, 0.25, 0.50, 0.75, 1.0, 1.25 and 1.5 molar to help me determine the best way sugar solutions effect potato cells. I predict, as same as before, that as the sugar solutions rise the number of change will become greater but will develop into a negative number. I will be controlling the amount of sugar solutions, length and weight of the potatoes. I am doing this so the result can be as accurate as possible. In order to find the most accurate way of measuring the change I studied the results I found in the preliminary investigation and finally decided to weigh the mass of the potatoes before and after to find out the best way the effect the sugar solutions have on potato cells. To carry out the main investigation I am going to: 1) Cut all potatoes to 4.5cm using a scalpel and borer 2) Weigh potatoes using scales, fill in data on table 3) Mark the potatoes 'A,B,C' with a marker pen 4) Pour 30cm3 of all 7 levels of sugar solutions (0, 0.25, 0.50, 0.75, 1.0, 1.25 and 1.5 ) into 7 test tubes using measuring cylinders. 5) Place 3 potato tubs in each solution 6) Leave them for 20 minuets timed using a stop watch 7) Take potatoes out of tubes using a sieve 8) blot potatoes dry with paper towels 9) Weigh and measure the potatoes using scales and a ruler 10) Record findings on the results table Main Investigation 0 molar sugar solution Potato Tube Weight Before Weight After Change Average Change A 2.57g 2.82g +0.25g 0.2g B 2.65g 2.82g +0.17g C 2.52g 2.70g +0.18g 0.25 molar sugar solution Potato Tube Weight Before Weight After Change Average Change A 2.59g 2.78g +0.19g 0.17g B 2.64g 2.75g +0.11g C 2.58g 2.80g +0.22g 0.50 molar sugar solution Potato Tube Weight Before Weight After Change Average change A 2.58g 2.74g +0.16g 0.17g B ...read more.

Conclusion

I have found that as the sugar solution began to get stronger the changes between the mass decreases gradually. As the solutions begins to get stronger the mass of the potatoes decrease. This happens because the amount of water in the potato becomes greater than the quantity of water in the solution as the solution strengthen. So the water from the potato moves from a region of low concentration(hypotonic) to a region of high concentration(hypertonic) through a partially permeable membrane to even out water balance making the potato shrink and the solution to become less concentrated. As an extension to this investigation, I would run two experiments in parallel. All cores would be from the same potato, but one would run for an hour, as this one did and for the other the cores would be left in the solutions for longer, perhaps 24 hours, to establish if one hour is the end point of the osmotic diffusion. Evaluation The experiment worked somewhat to what was expected and the method was fairly reliable and produced reasonably dependable results. There are a few things that I could have changed - I think we could have had a better method for drying the potato tubes because if a potato tube isn't dried properly then there is much more water on the tube at the start than another tube. This may affect the results and therefore may end up affecting the conclusion. Another thing we could have improved was to try and do each individual solution at the very same time. The problem with this is that we simply didn't have enough people to do this. As an extension to this investigation, I would run two experiments in parallel. All potato tubes would be from the same potato, but one would run for an hour, and for the other the potato tubes would be left in the solutions for longer, perhaps 24 hours, to see if one hour is the end point of the osmotic diffusion. I would also experiment with different temperatures to see if there was any more change. ...read more.

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