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Biology GCSE Coursework

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Introduction

Biology GCSE Coursework -PLANNING Aim: To find out the sugar concentration inside a potato cell. Introduction: Osmosis is the movement of water molecules from an area of high concentration to an area of low water concentration across a semi-permeable membrane. In animal cells, if the cell is placed into a more concentrated solution, the cell will crenate (meaning it will shrivel up). However, if the cell is placed in a more dilute solution, the cell swells and bursts. In plant cells, it is more complicated. In a more concentrated solution, the cell pulls away from the cell wall due to lack of water. This is called incipient plasmolysis. If the cell is then put pack into the correct solution of water, it will then return to normal. However, if it continues without water, then the cell will pull away from the cell wall completely. This is called total plasmolysis. The cell wall now has nothing supporting it, so they are not rigid. This is why a plant will wilt if not watered. On the other hand, if the cell is put in to a more dilute solution, the cell swells up. But unlike in an animal cell, the cell wall prevents the cell from bursting; instead the cell is just pushed right up against the cell wall. ...read more.

Middle

The first was it provided me with the size of cork borer that I need. I also showed me that I would need to do lots of repeats in my final experiment. The results I got from that were useful because they showed me that. In my final experiment I shall repeat results so anomalies are excluded and a trend recognised. Fair Test: In my final experiment I will need to keep these factors the same; the volume of liquid, the diameter of the potato chip (using the same cork borer throughout will solve this one) the length all the chips are in the solutions and the length of the chips. We are doing three repeats so that any anomalous results can be seen and 6 concentrations will allow us to plot a graph. Safety: In the experiment, there are a few things I will nee to look out for. Both scalpels and cork borers are very sharp, I should not cut/bore straight onto my hand or the table. Instead, I should use a white tile, this will prevent me from harming myself or the desk. Also, if any glass test tubes should break, I should be very careful and clear up. -ANALYSIS Conclusion: The trend of my results is as follows; at low sugar concentration the potato increased in mass, however at high sugar concentration the potato decreased in mass. ...read more.

Conclusion

This would mean that I could see what would happen in-between and not make assumptions. If I had more points from the intermediate stages, I could plot a more detailed graph, and therefore get a better line of best fit. The second thing I could do would be to do five repeats instead of the three that I did do. By doing this, any anomalies that did occur would be made clearer, and any mistakes that happen due to lack of data would not happen because there would still be four points left to use for calculations. Reliability of results: On the whole, I do not believe that my results were entirely accurate. The points I recorded in the actual experiment were close together, however it was not easy for me to draw a line of best fit. I do not think that they reliable enough to draw a firm conclusion, instead I was only able to gain a rough trend from the results. Further Work: If I was to continue this experiment further, I could do this experiment with a carrot instead of potato. This would be investigating to see if other root vegetables have the same sugar concentration as a potato. I could set up the experiment in exactly the same way as my main osmosis experiment. If I were to do this I would expect to find that the concentration is higher. I can predict this because a carrot tastes sweeter than your average potato. ...read more.

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