When a substance moves across the plasma membrane along a concentration gradient at a rate faster than would be expected by simp

The appropriate response is: Facilitated Diffusion. Facilitated Diffusion refers to how specific solutes, molecules, and other substances are moved across the plasma membrane using carrier proteins, following their concentration gradient (from areas of higher concentration to lower concentration). Carrier proteins are integral membrane proteins that span the lipid bilayer of the plasma membrane, facilitating transport by being open to both the interior and exterior of the cell. Polar molecules, such as glucose and charged ions, along with amino acids, are transported this way because the lipid bilayer cannot allow their direct diffusion due to their charge. This process happens along the concentration gradient, hence does not necessitate the use of metabolic energy.