Cell Membrane Structure

Question 1

Permiability of Cell Membranes

Answer 1

Cell Membranes are partially permeable. This means that some substances can pass through and some substances cannot

Question 2

Factors affecting cell membrane permiability

Answer 2

1. Temp

2. Conc of solvent

Question 3

Investigating Permiability of Cell Membranes

Answer 3

1. To investigate how temp. affects permiability of cell membranes, use beetroot cells.
2. Because they release a coloured pigement
3. The higher the permiability of beetroot cell membranes, the more pigement released
4. Cut up 5 pieces of beetroot. Ensure they are equal size (length, width, height). Rinse to remove any pigement that may have leaked out when the beetroot was being cut
5. Put each beetroot piece in a test tube. Ensure each test tube contains 5cm3 of water
6. Put each test tube in water baths at different temps, 10,20,30,40,50. For same amount of time. Time using stop watch
7. Then remove the test tubes from water baths and also remove the beetroot pieces, so you are left with just the coloured pigement solutions
8. Use a colorimeter. This is a machine which passes light through a solution and measures how much light is absobed. The higher the absorbance, the more pigement released from beetroot cells, the more permeable the membranes
9. The colorimeter will need 5 mins to stabalise before use and must be calibrated to zero by passing light through pure water