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effects of concentrations of sugar solutions on potato chip cells

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Introduction

Biology Coursework My task is to investigate the effects of concentrations of sugar solutions on potato chip cells. Planning My controlled variables are to be the temperature the experiment is performed at, the starting length of the potato chips, the total quantity of solution to be used and the amount of stirring for each test. The effects of these variables if uncontrolled are listed in the table below. Variable How it will affect the investigation. How it will be controlled Temperature The higher the temperature the quicker the experiment will be so if one test was to be at a higher temperature than another then the test would be unfair. Osmosis is not directly affected by temperature, although the general mobility of molecules increases with temperature, and this means a slight increase in osmotic effects with temperature. Also the rate of the experiment could be increased when heated due to the collision theory. The collision theory states that when an experiment is heated the particles and molecules will move quicker, therefore giving them a higher chance of moving through the partially permeable membrane of the cell membrane. I will control this by taking all the tests at the same time at room temperature. Starting length of chips The larger the surface area, the more osmosis occurs, therefore proving unfair if any chips have a different surface area to another. Any larger chips would have been able to diffuse out more or taken in more water molecules, depending on the concentration, because it is has a large inner area and surface area than the smaller chips. I will cut the chips so that they are all the same length, width and depth. ...read more.

Middle

The following table shows how these items will produce reliable results. Plan For my experiments I will use six different concentrations of sucrose solution: 0M, 0.2M, 0.4M, 0.6M, 0.8M and 1M. This will provide me with a large range of results, from which to base my analysis on. I will test each concentration three times, so in total will need 18 boiling tubes. I will always use a total of 20mls of solution. I will weigh and record the mass of each chip after cutting them all down to 5.3cms in length. This means I will be able to collect reliable data for my results. I will place all the chips in the solution as quickly as possible so they all have the same time. I will then leave them for 24 hours and then take them all out of their solutions. I will do this again as quickly as possible to make it a fair test. I will surface dry them with a paper towel to make sure I am only weighing the potato chip, rather than the potato chip and any excess solution. I will weigh each chip again so I can tell the mass change, and percentage difference later. These are how I will mix all my concentrations so they are all exactly the same. Concentration of sucrose solution/ M Volume of sucrose solution added/ cm3 Volume of water added/ cm3 0 0 20 0.2 4 16 0.4 8 12 0.6 12 8 0.8 16 4 1.0 20 0 I will carry out my experiment as shown in the plan above. The evidence I will collect is the mass change of the potato chips in the range of different solutions. ...read more.

Conclusion

This will mean that some chips would be in a lower concentration so the results would be affected. You can cover the tops of the boiling tubes with cling film and place them in a cool, dark place in a room. The chips might not have properly been dried. This would mean that you might be weighing at the end of the experiment the mass of the chips and excess sucrose solution. I could dry them with a paper towel and weigh them, then dry them again and reweigh and continue to do this for each one until I get a constant weight. Evaluation of Procedure I think my experiment went according to plan and the procedure I used was quite suitable. It was a fair test as all the chips had the same amount of sucrose solution, the same length of time and the conditions they were left in were all the same. There were more limitations to my experiment though: * Measuring cylinder - It would have been much more accurate to use a burette or graduated pipette. * Chips from different potatoes - Different potatoes have different dilutes and minerals, so some potatoes might have behaved differently. To improve on this you could take all your chips from one potato. I think the limitation that had the most significance was if the chips were not dried properly. If you did not take off all the excess water then the results would be different and incorrect. Next time, to improve my experiment I will use a burette or graduated pipette to measure out my concentrations of sucrose solution and make sure that I spend more time drying my chips after the experiment to ensure I get the maximum in reliability in my results. Page 1 of 7 Lizzie Wright ...read more.

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