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An Investigation into the process of Osmosis

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Paul Scanlon 26/1/2002 BIOLOGY SCIENCE COURSEWORK: "An Investigation into the process of Osmosis." Situation: "A chip shop owner wants to pre-prepare chips and soak them overnight without affecting their size. He has noticed that their size after soaking depends on the concentration of the glucose solution they have been left in." Aim: Therefore, my aim in this investigation is to find out the exact glucose concentration of a potato to help solve this situation. By doing this I should be able to determine the concentration of the potatoes themselves. Planning: Before actually planning the experiment, I will do some research to find out about osmosis, and matters related to it, so that I can make my predictions. This would leave way for me to figure out a way to make this investigation fair and safe. Planning ahead would help me find out how to do what and when to do it, which in turn should lead me to a set of good reliable results at the end of the experiment. Factors affecting the investigation: At this point in time, I cannot foresee many factors that could affect my experiment. But, there are some: * As there are no two identical potatoes anywhere in the world, it would be hard to try to equal the glucose concentration of the two chips taken from different potatoes. Therefore, I shall take all my chips from the same potato and hopefully, the single potato should have a glucose concentration equally throughout it. * Different temperatures may affect my experiment. ...read more.


4. By keeping the length of the time of the experiment the same, all the potato chips will have the same amount of time for osmosis to occur. If the times were varied, then osmosis could occur in one chip more than the other due to the time and the end results would be misleading and draw the reader to the wrong conclusion. 5. For the purpose of my experiment I am going to do all the experiments at room temperature. I have explained this earlier. 6. I am also going to use the same balance to weigh my potato chips. This is because the measurements may slightly vary between different scales. My Prediction: I predict that if the concentration of the water that the potatoes are submerged in is greater than that of the potato, the potato will swell up. If the concentration of the water solution is less than that of the potato, the cells in the potato will become plasmolysed. Hypothesis: Osmosis is the movement of water molecules from a weaker solution into a stronger solution, through a semi-permeable membrane. In this case, the tiny holes in the membrane of the potatoes will allow the water molecules to pass through in and out of the solution and the potato, depending on the concentration gradient of the two substances. So in this case, when the water concentration is lower in the tissue, the water will go inside the tissue of the potato, and the potato will gain mass. And if there is very little different in the two water concentrations, there shouldn't be such a big change in mass. ...read more.


6. I can then weigh every potato chip on an electronic balance and recorded the weights. 7. I will swiftly put 3 potato chips into each of the different molar concentrated beakers at two-minute intervals and then start my stop clock. The 3 chips that I am using for each of the different solutions will give me an average which will give me a better set of results and more accurate graphs. I will take the average of the three results for each of the individual solutions. 8. Whilst waiting, I can set out some paper towels with which I can dry the potato chips when they are done. Also, I can draw up a basic table for my results. 9. After 30 minutes I will drain out the solutions in the sink and place all the chips on the paper towel in the order I had put them in the test tubes as to not confuse myself as to which chip came from which solution. 10. I will dry each chip with the paper towel and then place each one on the scales so that I can weigh them. 11. Each potato will be measured accurately on the electronic scales and then the weights are to be recorded in my table of results. 12. If I have time after doing the first set of results, I can redo the experiment under exactly the same conditions. This would give me a secondary set of results that would give me a more accurate view on the changes. ...read more.

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