The primary barrier to passage of water-soluble substances across the plasma membrane is the outer layer of carbohydrates.

Question

Quizplus · Accepted Answer

The primary barrier to passage of water-soluble substances across the plasma membrane is the lipid bilayer, not the outer layer of carbohydrates. The lipid bilayer is selectively permeable and allows only certain molecules to pass through via passive or active transport mechanisms. Carbohydrates on the surface of the cell membrane can play a role in cell recognition and communication, but they do not serve as the primary barrier to water-soluble substances.

The Primary Barrier to Passage of Water-Soluble Substances Across the Plasma