5.1 Effective temperature on membrane permeability

Question 1

How do we test temperature against membrane permeability

Answer 1

1. Label 5 test tubes with temps 20 to 60, add 10cm3 distilled water to each and place in corresponding water bath
2. Cut Beetroot to give 5 30mm Cylinders then rinse and Pat dry
3. add the beetroot cylinder into each test tube in each temp and leave for 15mins
   5, Calibrate colorimeter with distilled water
4. Remove the tubes from the water bath and remove the cylinders from the tube
5. From each tube, pour liquid into a cuvette
6. Use the colorimeter to measure the absorption of each temperature and record

Question 2

Describe the relationship between temperature and the rate of leakage of pigment from the beetroot cells

Answer 2

As temperature increase rate of leakage increases

Question 3

Explain why leakage increases as temperature increases

Answer 3

The increased kinetic energy disrupts phospholipid structure of the membrane creating gaps and making the membrane more permeable allowing more to pass through

Question 4

What effect might a solvent such as ethanol have on membrane permeability

Answer 4

Ethanol dissolves lipids So destroys the bilayer letting a lot of pigment through

Question 5

Suggest one change that happens to the plasma membrane at temperatures above 60 degrees

Answer 5

Phospholipid structure disrupted
membrane proteins denature
membrane becomes more permeable

Question 6

Why did the cells lose their colour at high temperatures

Answer 6

At high temperatures membrane has become more permeable so the dye has released into solution