Question

How is the molecular composition of the cellular membrane responsible for selectively permeable barriers?

A. The lipid bilayer allows only water-soluble substances to pass through.
B. Protein channels facilitate the passage of large molecules.
C. Cholesterol maintains the rigidity of the membrane.
D. The hydrophobic tails prevent the entry of hydrophilic substances.

Answer 1

The cellular membrane is selectively permeable because of its phospholipid bilayer, which allows nonpolar molecules to pass and repels polar ones, with proteins aiding in the transport of larger or polar substances.

Step-by-step explanation:

The molecular composition of the cellular membrane is responsible for its selectively permeable nature due to the unique structure of the phospholipid bilayer. The hydrophobic tails of the bilayer allow small, nonpolar materials to pass through while repelling hydrophilic substances.

Proteins embedded in the membrane, including channel proteins and carrier proteins, facilitate the movement of larger or polar molecules that cannot pass through the bilayer on their own.