5. What kind of substances can't permeate membranes by
passive diffusion?
a) Lipid-soluble
b) Non-ionized substances
c) Hydrophobic substances
d) Hydrophilic substances

(d) hydrophilic substances this is because phospholipid has a polar head and nonpolar tails, so in passive diffusion, hydrophilic substances (charged polar molecules) can’t permeate membranes. hydrophilic would permeate membrane through active transport, not passive.