Which process does NOT require a protein facilitator?

Question

Quizplus · Accepted Answer

Simple diffusion does not require a protein facilitator as it involves the movement of molecules from an area of higher concentration to an area of lower concentration directly through the phospholipid bilayer. Ionophore-mediated diffusion, although involving a molecule (ionophore) that facilitates the transport of ions across the cell membrane, does not require a protein structure to function as a facilitator in the traditional sense used for membrane proteins. Thus, both processes can occur without the direct involvement of a protein facilitator.

Which Process Does NOT Require a Protein Facilitator