What is the significance of the phospholipid bilayer being two

phospholipid bilayer A cell membrane is a bilayer because it is made up of 2 layers of heads of the lipids are faced towards the opposites sides (the inside and outside

The cell membrane consists of a lipid bilayer that is semipermeable The cell membrane regulates the transport of materials entering and exiting the cell phospholipid bilayer bilayer membranes by lithographic polymerization of a diacetylene lipid phospholipid bilayer: Tethering as a new approach to substrate-membrane