Question

question 4 (2.5 points)
the relative impermeability of membranes to water soluble molecules is a result of the
nonpolar nature of water
presence of large proteins that extend through both sides of membranes
presence of inorganic salt crystals scattered through some membranes
presence of cellulose and waxes
presence of phospholipids in the lipid bilayer

Explanation:

The cell membrane is a phospholipid bilayer. Phospholipids have a polar head (hydrophilic) and non - polar fatty acid tails (hydrophobic). Water - soluble (polar) molecules have difficulty crossing the non - polar interior of the lipid bilayer. Proteins can help transport some polar molecules, but the basic impermeability to many water - soluble molecules is due to the non - polar nature of the phospholipid tails in the bilayer. Water is polar (so the option about non - polar nature of water is wrong). Large proteins (while they have transport functions) are not the main reason for the general impermeability. Inorganic salt crystals and cellulose/waxes are not relevant components of the plasma membrane for this property.

Answer:

presence of phospholipids in the lipid bilayer