Answer
The combining form means "easy".
Work Step by Step
The affix "facil" and the word "facile" both means easy. Facil can also be thought of as meaning "helped" or made easy. If a process is facilitated it is helped or made easy or made possible by some factors or agents. Some substances, especially small molecule and hydrophobic molecules diffuse with ease through cell membranes. Other substances need help to pass through the lipid bilayer into the cytoplasm. Facilitated diffusion is one mechanism for helping the polar and hydrophilic substances cross the selectively permeable cell plasma membrane. Glucose sodium and potassium ions are taken across cell membranes by integral membrane protein carriers.
