Final answer:
Cholesterol is an integral membrane protein that can increase the fluidity of the plasma membrane.
Step-by-step explanation:
The presence of cholesterol in the plasma membrane can increase the fluidity of the membrane. Cholesterol is an integral membrane protein that is embedded in the lipid bilayer. It acts as a buffer that prevents the fatty acid tails of phospholipids from packing tightly together, thus increasing the fluidity of the membrane.