Which of the following factors does not affect membrane permeability? a) the polarity of membrane phospholipids. b) temperature. c) the amount of cholesterol in the membrane. d) the saturation of hydrocarbon tails in membrane phospholipids.

The correct answer is: A) The polarity of membrane phospholipids

Factors that affect membrane permeability are

1. Chemicals :

Some of the organic solvents such as chloroform and ethanol can dissolve the membrane and thus, destroy the selective permeability of the membrane.

2. Temperature :

Too high temperatures denature the protein that are in the structure of the membrane destroying its selective permeability. On the other hand, too low temperature slows down molecule movements and the permeability decreases.

3. Cholesterol:

Increases the permeability by reducing the barrier formed by phospholipids’ heads

4. The saturation of hydrocarbon tails in membrane phospholipids:

Saturated fatty acids decrease permeability of the membrane because  they get very close together, which makes it harder for the molecules to pass through.