AP BIOLOGY

Detailed explanation-1: -Cholesterol keeps the fatty-acid tails of the phospholipids bilayer from sticking together, which contributes to the fluidity of the plasma membrane.

Detailed explanation-2: -Cholesterol influences the fluidity of the membrane, and it does so in a bidirectional manner; at high temperatures it decreases fluidity and at low temperatures it increases fluidity. At high temperatures, cholesterol’s flat, rigid structure limits phospholipid movement.

Detailed explanation-3: -Cholesterol interacts with the fatty acid tails of phospholipids to moderate the properties of the membrane: Cholesterol functions to immobilise the outer surface of the membrane, reducing fluidity. It makes the membrane less permeable to very small water-soluble molecules that would otherwise freely cross.

Detailed explanation-4: -Saturation with cholesterol smoothes the phospholipid-bilayer surface, which should decrease light scattering and help to maintain lens transparency.