Final answer:
The hydrophobic interior of protein-free lipid bilayers provides a barrier to the movement of water and ions, but the fluid nature of the bilayer allows for the diffusion of some particles. The hydrophobic tails of lipid molecules interact through dispersion forces, giving the membrane its fluidity. This fluidity enables functions such as the selective passage of substances through embedded protein channels.
Step-by-step explanation:
The hydrophobic interior of protein-free lipid bilayers provides a barrier to the movement of water and ions in and out of the cell. However, the fluid nature of the bilayer allows for the diffusion of some particles across the membrane. In addition, the hydrophobic tails of the lipid molecules interact with each other through dispersion forces, which gives the membrane its fluidity. This fluidity allows the membrane components to move about, enabling various functions such as the selective passage of certain substances through embedded protein channels.