Question

if the lipid composition of a cell membrane is changed to have a higher percentage of unsaturated lipids, what will be the effect on the number of water molecules moving across the membrane each minute?
more water molecules will pass through the membrane each minute because the permeability of the membrane has increased.
changes in the lipid composition will not affect the number of water molecules crossing the membrane each minute. it will only make it so that larger or more polar molecules will be able to cross.
changes in the lipid composition will not affect the number of water molecules crossing the membrane each minute because water is polar, so it requires a protein channel in order to cross.
fewer water molecules will pass through the membrane each minute because the permeability of the membrane has decreased.

Explanation:

Unsaturated lipids have kinks in their hydrocarbon tails due to double bonds. This prevents them from packing tightly together. A membrane with a higher percentage of unsaturated lipids is more fluid and has greater permeability. Water molecules can pass through the lipid bilayer (in addition to using aquaporins). Since permeability increases, more water molecules can pass through the membrane each minute.

Answer:

More water molecules will pass through the membrane each minute because the permeability of the membrane has increased.