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 leaks out into the surrounding solution within given time. A colorimeter can be used to determine the absorbance, hence concentration 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 different water baths ranging from 30 degrees- 80. Leave for 20 minuets.
4. 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 concentration 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 the temperature result in increase in membrane permeability.

Question 6

What is the effect of ethanol concentration on permeability?

Answer 6

Increasing ethanol concentration leads to increased membrane permeability.