🤓 Based on our data, we think this question is relevant for Professor McCleary's class at USF.
The lipid bilayer of plasma membranes is mainly composed of phospholipids. These lipid moclecules are amphipathic as they have a polar head aside from its nonpolar tail. This very nature of phospholipids would make it very unlikely (and high energy-requiring) for one phospholipid molecule to switch to the other monolayer as it would require the polar head to directly interact with the hydrophobic environment of the nonpolar tails.
Which of these is a general feature of the lipid bilayer in all biological membranes?
A. Na+ and K+ ions readily diffuse across the bilayer.
B. Individual lipid molecules in one face (monolayer) of the bilayer readily diffuse (flip-flop) to the other monolayer.
C. Individual lipid molecules are free to diffuse laterally in the surface of the bilayer.
D. The bilayer is stabilized by covalent bonds between neighboring phospholipid molecules.
E. The polar head groups face inward toward the inside of the bilayer.