Investigation to Determine the Effect of a Range of Different Concentrations of Sugar Solutions on the Potato Cells

Investigation to Determine the Effect of a Range of Different Concentrations of Sugar Solutions on the Potato Cells
Aim My aim is to set up an investigation to determine the effect of a range of different concentrations of sugar solutions on potato cells. I predict that the higher the concentration the more the length and mass of the potato chip will decrease. The lower the concentration the more the length and mass of the potato chip will increase. This should happen due to the law of osmosis. There will be a point at which nothing will change because the concentration inside and outside the potato is equal. The concentrations above this point will decrease, and as it gets weaker after that point will gain. Apparatus ? Measuring Cylinder x2 10ml ? Test tube x11 ? Test tube holder x2 ? Potato chips x11 ? Scalpel ? Top pan balance ? Ruler Method Firstly I will set up the apparatus as shown in my diagram. I will make up 11 solutions, which then I will pour a different concentration of each in each test tube. (Table below showing how I am going to make my solutions.) Test tube No. % Water (ml) 20% Sugar solution (ml) 1 0 10 0 2 2 9 1 3 4 8 2 4 6 7 3 5 8 6 4 6 10 5 5 7 12 4 6 8 14 3 7 9 16 2 8 10 18 1 9 11 20 0 10 I will then measure 11 potato chips with a ruler accurately and cut them to 30mm each with a scalpel, also I will weigh each potato and write down their mass.I will then put 1 potato chip into each of the 11 test tubes, and leave them for 24 hours. To make my test fair I will have to make sure that my potato chips are from the same kind of potato, make sure the environment and temperature is at the same. I will have to make sure that I do not move any of my potatoes while in the test tubes as this may effect the results. To ensure safety I will make sure there are no wet surfaces, and that all objects are out of the way. I will not use the potato as food after, as it has been in a lab. I will take care cutting the potato with a scalpel, and I will wash my hands after the experiment. A 1st aid kit should be nearby. Results === Test tube no. % Length before (mm) Length after (mm) Difference (mm) 1 0 30mm 34 +4 2 2 30mm 33 +3 3 4 30mm 31 +1 4 6 30mm 30 0 5 8 30mm 30 0 6 10 30mm 29 -1 7 12 30mm 32 +2 8 14 30mm 29 -1 9 16 30mm 28 -2 10 18 30mm 26 -4 11 20 30mm 25 -5 Anomaly [image] Test tube no. % Mass before (g) Mass after (g) Difference (g) 1 0 1.56 1.84 +0.28 2 2 1.53 1.79 +0.26 3 4 1.39 1.52 +0.13 4 6 1.40 1.49 +0.09 5 8 1.47 1.54 +0.07 6 10 1.42 1.31 -0.11 7 12 1.50 1.46 -0.04 8 14 1.48 1.44 -0.04 9 16 1.45 1.43 -0.02 10 18 1.49 1.41 -0.08 11 20 1.41 1.40 -0.09 Analysis From my results table I have found out that the stronger the solution the more length and mass will decrease. And the weaker the solution the more the length and mass will increase. This agrees with my hypothesis. This means the law of osmosis applies to potatoes. My range of results is +028g and -0.09g. Which is 0.37g. The results of changing mass show that there was a significant increase of 0.28g for the potato chip in the 0% sugar solution. The potato chip in the 20% sugar solution decreased in mass by 0.09g. At 13.3% sugar solution there was no change in mass. So there?s no net movement of water molecules in and out of the semi permeable membrane, as there is an equal concentration of water and solute inside and out of the potato cell. Therefore the concentration of sugar inside the potato chip must have been 13.3% As the concentration decreased from 13.3% the mass of the potato increased, as the concentration increases from 13.3% to 20% the mass of the potato decreases. The results of change in length shows that there was an increase of 4mm for the potato chip in the 0% sugar solution and the potato chip in 20% sugar solution decreased in length by 5mm. My range of results is 9mm At 8.9% sugar solution there was no difference in length, similarly there was no net movement of water molecules in and out of the potato cell at this concentration, therefore the ratio of water and solute molecules inside the potato cell, must have been equal to the ratio of water and sugar molecules outside the potato cell As the concentration decreased from 8.9%, the length of the potatoes increased, those results show that water must have travelled though the semi permeable membrane: from the outside of the potato, which was a high concentration, to inside the potato cell which had a lower concentration of water molecules. As the concentration increased the potato decreased this shows water moving from the outside of the potato cell to the inside. Therefore the law of osmosis is true and applies to potatoes. Evaluation == The anomalous result in the graph, which shows change in length, is at 12% sugar solution. The potato gained 2mm; if it had followed the line of best fit it should of lost approximately 1.5mm. The anomalous result in the graph, which shows the change in mass, is at 10% and 16% sugar solution. At 10% sugar solution the potato chip lost too much mass. And the potato chip in 16% sugar solution lost too little. Although I followed the procedure correctly, the potatoes themselves could have caused these anomalous results; as I couldn?t get 20 potato chips out of 1 potato, A number of potatoes of the same variety was used. Each separate potato might have had different water content at the beginning of the experiment. The first potato might have been 17% water and the second one might have been 9% water, etc. Another anomaly I found is that the point at which there is no net movement of water and solute molecules is different in each set of results. For the change in mass results it is 13.3% and for the change in length results, it is at 8.9%. This is because I am dealing with 100th of a gram compared to 1mm in each measurement. Therefore mass is more sensitive to change and a potato chip may take in or lose minute amounts of water without a noticeable change in length. To make this experiment more accurate I could use callipers, instead of a ruler for measuring the potatoes. This would reduce human error. To do further work on osmosis and gain more evidence, I could complete this same investigation with a different vegetable such as a carrot or turnip. I could also repeat this experiment using a slug instead of plants. I would use different concentrations of salt solution and see how much the slug changed in mass and length. However I will not do this experiment as it is not ethical.

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