Which of the following factors would tend to increase membrane fluidity?

a. a greater proportion of unsaturated phospholipids

b. a greater proportion of saturated phospholipids

c. a lower temperature

d. a relatively high protein content in the membrane

The correct answer is A.

Explanation:

Membrane fluidity can be increased by lipid chains with carbon-carbon double bonds (unsaturated phospholipids). They are more fluid than lipids that are saturated because unsaturated double bonds make it harder for the lipids to pack together.

Also higher temperatures can increase membrane fluidity because lipids acquire thermal energy, this results in many arranges and rearranges of the membrane and therefore makes it more fluid.