Identify true statements of cholesterol and its fluidity.1. Cholesterol decreases membrane fluidity in areas called rafts, which contain large amounts of sphingolipids and cholesterol.2. Cholesterol inhibits crystallization that would otherwise occur in membranes rich in unsaturated fatty acids.3. Cholesterol is generally buried in a bilayer, with its planar rings oriented toward the solvent and its hydroxyl group aligned with the fatty acid tails of the bilayer.4. Cholesterol increases membrane fluidity that otherwise contains mostly long chain saturated fatty acids.

The correct answer is 2. Cholesterol inhibits crystallization that would otherwise occur in membranes rich in unsaturated fatty acid.

Explanation:

Cholesterol is a very important complex constituent of plasma membrane. It regulates the membrane fluidity at both high and low temperature.

Cholesterol acts as a bidirectional regulator of membrane fluidity because at high temperatures, it stabilizes the membrane and raises its melting point, whereas at low temperatures it intercalates between the phospholipids and prevents them from clustering together and stiffening.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

the answer is c i believe