RP4 - Investigating Cell Membrane Permeability

Question 1

State 2 factors that affect the permeability of cell

membranes.

Answer 1

Temperature

Concentration of solvents (ethanol)

Question 2

How is beetroot used to measure the permeability of

cell membranes?

Answer 2

The higher the permeability, the more red pigment that leaks out into the surrounding solution within a given time.
A colorimeter can be used to determine absorbance, hence conc of pigment.

Question 3

Outline the procedure to investigate the effect of

temperature on permeability of cell membrane.

Answer 3

1. Cut beetroot into 6 identical cubes with a scalpel.
2. Place each cube in a different test tube with equal volumes of distilled water.
3. Place each test tube into water baths ranging from 30-80°C.
4. Leave for 20 minutes.
5. Filter each solution out into a cuvette and measure the absorbance using a colorimeter.

Question 4

What are the safety hazards involved in testing the

effect of ethanol conc on membrane permeability?

Answer 4

Ethanol is an irritant and is flammable, keep away from naked flames, wear eye protection.
Keep sharp scalpel away from fingers.
Handle hot liquid with care.

Question 5

What is the effect of temperature on membrane

permeability?

Answer 5

Increasing temperature results in increase membrane permeability.

Question 6

What is the effect of ethanol concentration on membrane permeability?

Answer 6

Increasing ethanol concentration leads to

increased membrane permeability.