Aim: To investigate osmosis in plant cells.
Introduction: In this investigation I will be looking at osmosis in potato cells.
What is Osmosis?
Osmosis is a special case of diffusion. Movement of substances take place through the cell membrane which separates the cell contents from the surroundings. Cell membranes are partially permeable, this means that they allow some substances to pass through and stop other substances from passing. When two solutions are seperated by a partially permeable membrane, water passes through the membrane in both directions, but the net movement of the water is from the more dilute solution to the more concentrated solution. The water flows until the two concentrations are equal. This process is called Osmosis.
I predict that the potato will increase in size and weight most when it is put in 100% pure water (0% sugar solution). I predict this because I know that in osmosis, the water travels towards the more concentrated solution. As pure water is more dilute than the solution in the potato's cell sap . This would mean that the water particles will move into the potato. This will therefore make the potato cells swell up. Cells in this condition are described as Turgid.
I also predict that the potato will decrease in size, and hence weight the most when it is put in 15% sugar solution which is most concentrated. I predict this because I know that the concentration of the solution in the potato is less than 15% and in osmosis, the water moves towards the more concentrated solution, in this case, this will be the solution around the potato. This means that the water will move outwards from the potato, making it lose water. This will cause the potato to shrink. Cells in this condition are described as Plasmolysed.
I also predict that when the concentration of the solution outside the potato is stronger and the potato decreases in size, the amount of solution in the test tube will increase. I predict this because I know that when the concentration is stronger outside the potato, the water will move out from the potato and add to the amount of solution
1 potato borer
1 measuring cylinder
10 test tubes
1 test tube rack
15% sugar solution
Firstly, I will cut out 10 pieces of potato, using a potato borer. Using a knife and ruler, I will cut each piece of potato so that it is 4cm long and 3g in weight. Each piece of potato will be...