Which of the following substances is most likely to passively diffuse across the plasma membrane by dissolving in the membrane?
A) a cation
B) an anion
C) a nonpolar or nonionized molecule
D) a polar molecule
E) a molecule less than 0.8 nm in diameter

Question

Quizplus · Accepted Answer

Nonpolar or nonionized molecules are more likely to dissolve in the hydrophobic interior of the plasma membrane and passively diffuse across the membrane without the need for a transport protein. Polar molecules and ions tend to interact with the polar head groups of the membrane and require transport proteins to cross the membrane. The size of the molecule is not the determining factor for passive diffusion, but rather its polarity and charge.

Which of the Following Substances Is Most Likely to Passively