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Investigate the transportation of water in living cells through the process of Osmosis

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Introduction

Rachel Tsang 10S1/10H1 Osmosis: Osmosis is the movement of water from a high concentration of water to a low concentration of water through a semi-permeable membrane. These semi-permeable membranes are found in cell membranes, they allow some things to pass and stop other things from passing through. It usually only allows small molecules to pass, e.g. water, but not things like starch and proteins, these must be broken down, through enzymes first. We could say osmosis is the transportation of water from a dilute solution through a semi-permeable membrane to a more concentrated solution. Aim: I am going to investigate the transportation of water in living cells through the process of Osmosis. I am going to plan and carry out an experiment to investigate this on potato cells. Once I have gathered my results and using my own knowledge, I hope to explain why certain things will happen and the consequences of osmosis. Experimental Design: There will be certain factors in my experiment that will probably affect the results of my experiment. I have to consider in mind, when conducting the experiment, if the surrounding temperature will affect the result or not. If the temperature is more warmer, the water and glucose molecules might move faster as the temperature rises, and could cause an effect in the way they pass through the semi-permeable membrane, the process could decelerate or accelerate. I would also have to consider how long am I going to leave the chips in there for, the longer it's left ...read more.

Middle

4. Put the borer cork into a potato, make sure hands are well clear, from the end of the potato, which the cork is going to come out at. Take out cork, and push chip out and place on the tile. 5. Place each chip on the balancing scales in turn, and weigh each one, making sure each one weighs 2.5grams. Use scalpel to cut chips to right mass, BECAREFUL WHEN USING THE SCAPEL! 6. Place one chip in each test tube, try to make sure, you drop them in roughly at the same time. 7. Start the stopwatch and leave potatoes in there for an hour. 8. Drain the solution from each test tube and weigh each of the chips in turn and record the results. 9. Repeat steps 4-8 twice to get two more sets of results. Results Table: Moles (m) Mass Start (g) Mass After 1 (g) Mass After 2 (g) Range (g) Mass After 3 (g) Average (g) Percentage increase/ decrease% (between average and start mass) 1 2.5 1.94 1.91 0.03 2.03 1.96 -21.6 0.8 2.5 2.31 2.18 0.13 1.75 2.08 -16.8 0.6 2.5 2.23 2.20 0.03 2.10 2.18 -12.8 0.4 2.5 2.38 2.30 0.08 2.23 2.30 -8 0.2 2.5 2.60 2.59 0.01 2.63 2.61 4.4 0 2.5 2.83 2.71 0.12 2.74 2.76 10.4 My graph shows me, that more sugar in the solution, the less water is taken from the potato. The lines on the graph are decreasing, but not dramatically, as the amount of sugar is increasing. ...read more.

Conclusion

If I had to do this experiment again, then I would definitely leave the potatoes in the solutions for at least 2 hours, if not longer. This would then give me a better set of results to draw up a more accurate conclusion. I would also make sure that I would get a better timer, to time how long I leave them for. I could do the experiment four times in total, to try and get a better average. I could also have a look at how the temperature might affect the speed of osmosis. Molecules move faster at a higher temperature, therefore it could speed up the rate of osmosis. So I would have to record the surrounding temperature and do another batch somewhere with a higher/lower temperature to see if it makes any difference at all. This will then enable me to plan my experiment more carefully and to allow more accurate results. I could also see how different varieties of potatoes, grown in different surrounding environments can affect the outcome of the results. I could do a separate experiment for this, which then can lead me back to my original experiment to put these factors into perspective, so I can consider them, while doing the experiment again. WWW.GOOGLE.COM ( Search for OSMOSIS) WWW.ASK.CO.UK (Search for OSOMOSIS) WWW.BBC.CO.UK/ SCHOOLS/GCSEBITESIZE/BIOLOGY Comptons Interactive Encyclopedia Encarta Nelson Balanced Science- The Living World Covent garden books- The Science Encyclopedia Class notes AQA Revision guide CGP Biology Revision Guide ?? ?? ?? ?? Rachel Tsang ...read more.

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