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The coursework that I have been set is to design an investigation to find out the concentration of sugar solution that causes no real change in mass to a potato chip due to osmosis.

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Introduction

G.C.S.E Biology coursework Osmosis PLAN The coursework that I have been set is to design an investigation to find out the concentration of sugar solution that causes no real change in mass to a potato chip due to osmosis. Osmosis is the movement of water molecules through a partially permeable membrane due to a concentration gradient. Water moves from one area with a low concentration to an area with a high concentration. If you place a plant in water, then water will move into the plant cells by osmosis; * The cell membrane of the plant cell acts as a partially permeable membrane. * The cell sap inside the vacuole has a high concentration. * Water passes into the cell by osmosis. * The concentration of the sap in the vacuole is now weaker. * Water passes from the weak solution into the strong solution in the next cell by osmosis. When potatoes are placed into a sugar solution. Osmosis takes place, if a potato is placed into a more concentrated sugar solution, water will move out of the potato and into the sugar solution, this why the potato will get lighter - there is less water in the potato. ...read more.

Middle

The table will look this, concentration start weight (g) end weight (g) % change (M) 1 2 3 average 1 2 3 average 0.25 0.3 0.35 0.4 0.45 0.5 If my results are correct then my graph should look something like this, These are the results that I got from the investigation. concentration start weight (g) end weight (g) % change (M) 1 2 3 average 1 2 3 average 0.25 4.1 3.26 3.26 3.68 4.14 2.92 3.32 3.73 1.36 0.3 4.14 3.21 3.1 3.68 4.12 3.21 3.29 3.67 -0.27 0.35 4.18 3.23 3.11 3.51 4 2.98 3.09 3.36 -4.46 0.4 4.17 3.35 3.05 3.52 3.68 2.91 2.77 3.12 -11.36 0.45 4.14 3.18 3.19 3.5 3.5 2.48 2.86 2.95 -15.71 0.5 1.8 3.35 2.95 3.49 3.47 2.78 2.54 2.93 -16 The results of chip 2 in the 0.25M solution and chip 3 in the 0.3M solution were both anomalous. That is why there is it is shaded in the table. Here are the anomalous results. Concentration Start Final 0.25 3.26 2.92 0.3 3.1 3.29 The first anomalous result loses weight when the other results for that concentration gain weight and the second anomalous result gains weight when the other results for that concentration lose weight. ...read more.

Conclusion

To weigh my chips, I used an electronic scale correct to 2 d.p. but the last decimal place rarely settled and the number continuously changed. I decided to keep it to two decimal places because if the reading I got was 2.23 2.24 2.25 then any one of those readings is more accurate than 2.2 or 2.3. I have already mentioned my two anomalous results, the first anomalous result loses weight when the other results for that concentration gain weight and the second anomalous result gains weight when the other results for that concentration lose weight. This could have happened in a number of different ways, the chips could have more/less surface area so the rate of osmosis is changed, the chips could have been placed in the wrong solution or I could have weighed them incorrectly. Looking at my results, I see that only one of my results gained weight so it might have been better to change the 0.45M and the 0.5M solutions to 0.15M and 0.2M solutions. To improve my results, I should pool them with others to get averages and more accurate results. To extend my investigation, I could look at Osmosis in different plant cells such as carrot or cauliflower cells and I could look in animal cells as well. ?? ?? ?? ?? David Jacques ...read more.

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