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Aim: To investigate the process of osmosis in potato cells.

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Biology Coursework Planning - Osmosis in Potatoes Aim: To investigate the process of osmosis in potato cells. Key factors and planning an investigation which is a fair test The different factors which affected the process are: * Using 2 potatoes, so tubes came from different potatoes. * When drying the potato cylinders for excess solution, some of the tubes may have been dried more, so therefore will weigh less. * When cutting the potato tubes, some of the cells may have been damaged. * The potato tubes were not put in the solution at the same time, so some tubes start osmosis before other tubes making it unfair. * The shape of the potato. The different factors which I will be trying to keep the same are: * Measuring the same amount of solutions in each test tube. * Cutting the potato tubes all to the same length. * Using all three tubes from the same potato. * Making sure that I put all three tubes into the test tubes at the same time. The factors which are going to be beyond my control are: * The temperature conditions. * The pressure of the solution * The volume of the solution * The surface area of the potato Prediction & Background I predict that the mass of the potato in a sucrose solution will decrease because water will diffuse by osmosis. ...read more.


After adding the solutions shown above to the three boiling tubes by using the squeezy bottle with water in it and a syringe for collecting the sucrose solution from the beaker, I measured these in a measuring cylinder to get the right amount of volumes. Also labelling each molar solution on the boiling tubes with a permanent marker so that I knew which was which, I added one potato cylinder to each boiling tube. Making sure that each one was fully covered in each solution. I tried to put all three potato cylinders in at the same time. So it would be fairer if all of them started osmosis at the same time. 6) Next, I covered each boiling tube with a cling film, so that nothing would affect my experiment of osmosis. Also nothing would evaporate from the potato causing the concentration to increase. 7) I then left these boiling tubes on a test tube rack with my name on it, for a few hours until osmosis had occurred in the potatoes. Preliminary Results: Molar Solution (M) Mass Before (g) Mass After (g) Length Before (cm) Length After (cm) 0 4.49 5.09 5.5 5.8 0.5 4.45 3.81 5.5 5.1 1 4.51 3.06 5.5 5.0 Water Solution Molar solution (M) ...read more.


Scales This also has a Petri dish on it to weigh the potato cylinders. White Tile For when I was using the potato borer to cut out cylinders, so that I wouldn't cut myself. Clingfilm To wrap my boiling tubes with, after I've put the potato and the right solutions in. Apparatus: Osmosis is the diffusion of water molecules from a high to a low concentration, therefore water molecules from inside the potato cylinder will move out into the solution. Leaving the cytoplasm inside the cells to shrink and become flaccid. As the cells of the potato cylinder lose water they then weigh lower than they did before. They also become shorter than they were before. In other words, when a potato cylinder is placed in a solution that has a higher concentration than the cylinder itself, the potato cylinder will lose weight (0.4, 0.6, 0.8 and 1.0 molars), because there is higher concentration of water molecules inside the potato compared to the ones outside the potato. In the same way when the potato cylinder is placed in a solution that has a lower concentration than itself, the potato cylinder will gain weight (0.0 and 0.2 molars), because there is a lower concentration of water molecules inside the potato cylinder compared to the water molecules outside the potato cylinder. 1 This picture is from Google images uk.encarta.msn.com/, describing the movement of water and sucrose molecules in osmosis. Anil Vaghela 10SAC ...read more.

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