REQUIRED PRACTICAL 4

Question 1

State 2 factors that affect the permeability of cell membranes.

Answer 1

Temperature and concentration of solvents (e.g., 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 a 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. Prepare test tubes with equal volumes of distilled water.
2. Place each test tube into water baths ranging from 30-80°C. Leave for 20 minutes.
3. Filter each solution 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 flammable; keep away from naked flames and wear eye protection. Keep sharp scalpel away from fingers and handle hot liquid with care.

Question 5

What is the effect of temperature on membrane permeability?

Answer 5

Increasing temperature results in increased membrane permeability.

Question 6

What is the effect of ethanol concentration on membrane permeability?

Answer 6

Increasing ethanol concentration leads to increased membrane permeability.