The biological membrane is described as fluid because the phospholipid molecules and proteins can move within the lateral plane of the bilayer.

Cholesterol is present in the bilayer because it is a non-polar, hydrophobic molecule.

The lipid bilayer is so called because it is composed of both lipids and proteins.

The carbohydrate chains of glycolipids and glycoproteins are found on the intracellular surface of the membrane.

The lipid bilayer of biological membranes is formed by phospholipid molecules with hydrophilic tailgroups and hydrophobic headgroups.