s the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion. Diagram showing facilitated diffusion across the plasma membrane. A channel protein embedded in the membrane allows yellow balls to travel through a channel from the outside of the cell to the inside. A carrier protein embedded in the membrane undergoes a shape change allowing red balls to travel from the outside of the cell to the inside. Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers.