BIOLOGY COURSEWORK
PLANNING
INTRODUCTION- During this investigation I am going to find out how osmosis affects potato cells. Osmosis is the of water -or any other solution- through a , from a region with high water concentration to a region with a low water concentration. The movement will take place across a cell wall- a semi-permeable membrane; in this case the potato cell, which lets smaller molecules such as water through but does not allow bigger molecules to pass through. So I will investigate this by using 5 slices of potatoes of the same mass and inserting them into 5 different concentrations of a sugar solution. At the end of the investigation I hope to see how much of the sugar solution is absorbed into the potato slices.
EQUIPMENT-
- 3 potatoes
- Scales
- Ruler
- Knife
- Chopping slate
- 10 Test tubes
- 2 Test tube racks
- 5 concentrations of a sugar solution. (Ranging from 0%-10%)
METHOD- I will set up 10 test tubes, because in order to save time, I intend on doing the test twice so that I can calculate the average result, making it more accurate. After I set up the ten test tubes in the two test tube racks (5 each) I will label each test tube. Both racks will have a test tube labelled 0%, 2.5%, 5%, 7%, 10% and either test 1 or test 2. I will then pour 250ml of the readymade solutions into the correct test tubes. After this is complete and I have 2 test tubes of 250 ml for each solution, I will use the knife and chopping slate to cut ten slices of potato from the three potatoes and the ruler to measure it so they are the same length. After I have ten slices of potatoes of the same length I will put them onto the scales one by one and record the mass of each slice before the investigation. I will put the recordings into a results table and then put a slice of potato into each test tube. When I have done this I will leave the potato slices in the test tube for a day and then come back for them, after this I will take one test tube and record the concentration and which test it is from the label into my results table. I will then take the potato slice from the test tube and pour the solution down the sink and using a paper towel I will dry the potato. After that I will weigh the mass of the potato slice using the scales and then record that into my results table also. I will then repeat this till I have the mass of each potato slice recorded in my results table.
