Flip-Flop Diffusion The inner leaflet (monolayer) of the human erythrocyte membrane consists predominantly of phosphatidylethanolamine and phosphatidylserine. The outer leaflet consists predominantly of phosphatidylcholine and sphingomyelin. Although the phospholipid components of the membrane can diffuse in the fluid bilayer, this sidedness is preserved at all times. How?

Explanation:

The movement of lipids or proteins from one leaflet to the other leaflet of the plasma membrane is known as flip flop movement or flip flop diffusion. Different phospholipids are present in different leaflets of the plasma membrane. These components of the plasma membrane does not flip flop compared to lipids and proteins which moves from one leaflet to another. This is because they are charged molecules with polar head. There movement needs more energy to cross the lipid bilayer which is hydrophobic in nature.

the answer is d. embryo