Q. How does the intensity of facilitated diffusion differ in relation to the concentration of the moved substance? What is limiting factor?

Like simple diffusion facilitated diffusion is supplementary intense when the concentration gradient of the substance less and increases intense when the gradient lessens. In facilitated diffusion however there is a limiting factor: the quantity of the permeases that facilitate the transport throughout the membrane. Even in a situation in which the concentration gradient of the diffusing substance enhance, if there are not enough permeases to perform the transport there will be no increase in the intensity of the diffusion. This situation is known as saturation of the transport proteins and it represents the point at which the maximum transport capacity of the substance across the membrane is achieved.