What does not describe a biological membrane?

A biological membrane is not a static lipid bilayer.

Explanation:

A biological membrane also called the plasma membrane is not just a lipid bilayer.It is specifically called a Phospholipid Bilayer.It is composed of :A glycerol moiety which is attached by three ester bonds with,One Phosphate moiety.Two chains made up of Fatty acids (both saturated and unsaturated).The fatty acid chains being hydrophobic in nature face towards the interior of the bilayer and the phosphate groups being hydrophilic in nature face towards the outer side.The phospholipid bilayer is also interspersed by integral membrane proteins, carrier proteins and membrane associated proteins and also cholesterol molecules.The bilayer is not static, it is fluid in nature. This means that the lipid molecules and proteins can laterally displace and move from their place in the membrane.The fluidity of the membrane is accounted by the unsaturated fatty acids that have bends or kinks in the chain ( saturated fatty acid has straight linear chains). These bends promote movement in the chains, thereby making the membrane fluid in nature.