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Investigate the use of Osmosis in potatoes

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Introduction

Investigate the use of Osmosis in potatoes Aim: I will investigate how osmosis occurs and the effect of osmosis and the diffusion of salt to water and how the rate of osmosis changes. I will want to check the independent variables and independent variables and finally I will need to check the mass of the potato before and after the experiment. Equipment needed: 2/3 potatoes, cork borer, ruler, beaker, thermometer, potato cuttings, scales/TBP, measuring cylinder, pure water, timer, and a calculator. Prediction: I predict that the potato will take in more water when put in a high concentration of water. I think this because the theory of osmosis states that water will pass from a dilute solution i.e. a high concentration of water, to a more concentrated solution i.e. a low concentration of water through a partially permeable membrane. A partially permeable membrane is a cell membrane that only allows some molecules that are small enough to fit through the tiny holes e.g. water, through. It therefore prevents the passing through of molecules that are too big e.g. sucrose. The water can pass through the cell membrane in both directions but is likely to balance the amount of water in the container with the amount in the potato cell. ...read more.

Middle

* Group them into 6pairs and weigh each pair noting the average mass down to 2 decimal points. * Put each pair in separate containers. * Measure out 6cm3 of 0.0molar glucose concentration i.e. water and pour it into a container with a pair of cuttings, ensuring that the cuttings are completely covered by the solution. * Label the container with the amount of glucose concentration. * Then measure out 6cm3 of 0.2m of glucose concentration and put it in a container with a pair of potato cutting and label it. * Do the same for 0.4m, 0.6m, 0.8m, and 1.0m. * Leave the containers for 24 hours and then re-measure the size and mass of each potato cutting, noting the average of each pair to see if they have changed. * Measure how much liquid is left in the containers. * Repeat the whole experiment 3 times to ensure that it is a fair test and to ensure that accurate averages will be used in the graphs. Preliminary Experiment Concentration of Sucrose Vol. cm3 Average mass of cutting before experiment (g) Average length of cutting before experiment Average mass after experiment (g) ...read more.

Conclusion

I could have measured more accurately by having a larger scale on my measuring cylinders. Also, I could have found a way of drying the potatoes without losing too much of the solution, so that there would be an accurate amount of liquid remaining in the container after the experiment. I could have done more experiments in order to have a more precise average plotted on my graph. I could also have timed the experiment more accurately since each of the repeats may not have been exactly 24hours. Using two potato cuttings in each container was slightly inefficient as they weren't identical causing inaccuracies. The containers were moved around. This may have affected the rate at which the water diffused in and out of the cells and may have affected any evaporation. The movement of the containers could also have changed the environmental conditions causing inaccuracies. All these factors may have affected the quality of my results and could be improved on. So, although the results were fairly accurate, there were more considerations that should have been thought of to add to the result's reliability. Therefore my conclusion is that there is sufficient evidence to say that the results show correct osmosis in action yet, the results seen by osmosis could have been more accurate ...read more.

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