The cell membrane consists of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins. This bilayer creates a hydrophobic region between two layers of lipids, making it which of the following?

An impermeable membrane would not allow any substances to pass through, which is not the case for cell membranes. While the lipid bilayer does restrict certain molecules, it is not completely impermeable; small nonpolar molecules can pass through, and various channels and transporters facilitate the movement of specific ions and molecules.

A permeable membrane would allow all substances to freely pass through without restriction. However, the cell membrane does not fit this description because it selectively permits certain molecules to enter or exit while blocking others, thus maintaining the necessary environment for cellular function.

While "selectively impermeable" might imply that some substances can pass through, it suggests a level of restriction that is too absolute. The term inaccurately conveys that the membrane is more restrictive than it actually is, as it does allow specific molecules to enter and exit based on size, polarity, and the presence of transport proteins.