Which of the Following CANNOT Diffuse Through the Plasma Membrane

Question

Which of the following CANNOT diffuse through the plasma membrane?
A) lipid-soluble molecules
B) water-soluble ions
C) proteins
D) water

Accepted Answer

Proteins are too large to diffuse through the plasma membrane without the assistance of specific transport mechanisms. Lipid-soluble molecules, water, and small water-soluble ions can all diffuse through the plasma membrane.