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GCSE Biology CourseworkTHE EFFECTS OF GLUCOSE CONCENTRATION ON OSMOSIS IN POTATO CELLSPrepared by:Bhavin PatelTh...

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Introduction

Apparatus: - * Potato * Blade * Cork borer * Stopwatch * Glucose solution * 50cm3 Measuring cylinder * Electronic Balance (scale in grams) * Five 200cm3 beakers * Forceps * Labels * Water bath Procedure: - * First cut the potato into half * Using the cork borer cut the potato to obtain five cylinders of potatoes (Make sure that the potato cylinders are from the same potato as the potato tissues maybe different from different aged potatoes) * Cut the potato cylinders down to the same length * Measure the mass of the each potato cylinder * Note down all your results in the table shown below Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Mass of potato before experiment (g) Mass of potato after experiment (g) Difference of mass of potatoes.(g) * Use five different concentrated glucose solutions:- * 2% glucose solution * 4% glucose solution * 6% glucose solution * 8% glucose solution * 10% glucose solution * Set up 5 beakers and pour the glucose solution in to them * Using a measuring cylinder, measure 20cm3 of each of the solutions and pour it into the beakers. * Label the beakers according to the concentration of the solutions. * Add the potato cylinders to the solutions * Immediately time the experiment for fifteen minutes(make sure that all the experiments are timed for the same period) * After fifteen minutes, remove the potato cylinders from the beakers * Wipe off any excess solution off the cylinders * Using the electronic balance measure the mass of the potato cylinders * Note the mass down in the table at the end of the first page. ...read more.

Middle

I used the electronic balance to measure the mass of the potatoes and noted the masses down in a table similar to the one show in the plan. Using the measuring cylinder I measured 20cm3 of sugar solution and found it to be too little, so had to measure 30 cm3 more to make the sugar solution to 50cm3. Got the stopwatch ready to time and slipped the potato cylinders into the beakers and started the stopwatch and then took the beakers to the water bath. I had planned to keep the water bath at the temperature of 35 degrees but as many other people in the class were doing the experiment I had to use 40 degrees. According to the plan I timed the experiment for 15 minutes. After 15 minutes I removed the solutions from the water bath and then removed the potato cylinder from the beakers one by one using the forceps. I wiped off the excess sugar solution off the potato cylinders using paper towels. I then measured the mass of each potato cylinder and noted down the masses on the table. I then calculated the mass differences of each experiment. For the second time, I had to use a different potato as I was doing it on another day. I repeated the same process I had used for the previous day. After I had noted down the masses after the experiments I calculated the change in mass of the experiment. ...read more.

Conclusion

I think this is because as we did the experiment over 3 days, we did not have a chance to use the same potato as I had planned to do. All potatoes do not have the same tissue structure and also concentration of sugar in different potatoes is different. I am sure that excess solution cannot be the reason for anomalous results because I wiped it off before I measure the mass of the potatoes. I believe that another reason for there to be anomalous results is that as I was the only person working on the experiment, some of the experiments stayed in the solution longer than the others. I believe this can affect the reliability of my results. Lastly I think that if I was provided with better equipment to work with than I could make this experiment more accurate and reliable. Below is a graph to compare the reliability of my results. Below is a graph comparing the results of the two experiments I carried out. From the graph above I can see that my results are reliable as both the lines are very similar. My results could be improved if I was able to use a larger range of concentrations and have smaller intervals with in then. I would have also liked to carry out the experiment for a longer time so that I could have larger figures to which I could work with. I could also repeat the same experiment but this time with different aged potatoes so that I could compare the result of both experiments. ...read more.

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