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In this experiment I am intending to investigate the concentration of sugar in the cell sap of a potato-cell's vacuole. I will discover this using my knowledge of the biological process ofOsmosis.Osmosis is the movement of solvent (usually w...

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Introduction

PLAN In this experiment I am intending to investigate the concentration of sugar in the cell sap of a potato-cell's vacuole. I will discover this using my knowledge of the biological process of Osmosis. Osmosis is the movement of solvent (usually water) through a semi-permeable membrane separating solutions of different concentrations. The solvent passes from a more concentrated solution to a less concentrated solution until the two concentrations are equal. Many cell membranes behave as semi-permeable membranes, and osmosis is a vital mechanism in the transport of fluids in all living organisms, the transport of water from the roots up the stems of plants is just one of these. APPARATUS For this experiment I will need the following apparatus: 1. One large potato, 2. Five glass beakers, 3. One measuring cylinder (50ml), 4. One potato corer, 5. One dissection tile, 6. One scalpel, 7. One measuring scale (2dp) 8. Ruler (1dp). To discover the concentration of sugar in the cell sap I will place a piece of potato, exactly 2.5cm in length, in a beaker of salt solution (varying in strength) and leave it for 24 hours. If the piece of potato increases in weight, the concentration of water in the solution is too low, therein, if it decreases in weight the concentration of water in the solution is too high. But if there is no change in weight whatsoever then the concentration of water in the solution is precisely equal to that of the cell sap. ...read more.

Middle

and I must repeat each concentration (so that I can identify any anomalous results and repeat that concentrate). I have chosen to repeat each stage three times, and I will look for the potato concentrate between 0% and 40% sugar concentrate (with a separate experiment for each 10%) as I thought is more likely that concentration of the cell sap will be under 50% concentrate than over. I chose to record the weight change in the potato sections to a 2 decimal place maximum as that will be close enough to detect any change in mass. I will measure the length of each piece of potato to only one decimal place, this measurement does not need to be too accurate as a difference of 0.1cm will not vary the results too much. SAFETY This experiment does not include any dangerous chemicals therefore it safe enough to not wear safety goggles. To ensure safety any sharp equipment that is needed during the experiment, i.e. Scalpels and potato corers, are to be used carefully on the surface of cutting tiles or boards. PREVIOUS KNOWLEDGE Through my previous knowledge I know that if the concentration of water surrounding the potato sector is greater than that contained within each potato cell's vacuole, through the process of osmosis water will pass over semi-permeable membrane and enter the potato cell thus increasing the weight of the potato sector. ...read more.

Conclusion

Therefore there is no area of high concentration and no area of low concentration; this means there is no movement. 30% At this concentration I believe that the potato will begin to decrease in weight because there is once again very little difference between the concentration of water inside the cell and the concentration outside the cell. I believe the potato will decrease in weight because the concentration of water is now a higher inside the cell than outside. Therefore, due to Osmosis, the water molecules will move from where they are in high concentration to where they are in low concentration: leaving the cells and entering the solution. 40% At this concentration I believe that the potato will decrease in weight because there is a high difference between the concentration of water inside the cell and the concentration outside the cell. I believe the potato will greatly decrease in weight because water is now at a much higher concentration inside the cell than outside. Therefore, due to Osmosis, the water molecules will move from where they are in high concentration to where they are in low concentration: leaving the cells and entering the solution. COLLECTION OF RESULTS To be sure that my results are collected and recorded in the correct manner, one which is easy to both understand and compare, I have constructed four results tables which can be seen overleaf. I have crated a separate table for every experiment and one in which I can record the average result of each aspect of those experiments. ...read more.

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