Facilitated diffusion is necessary in all the condition in which they are not able to pass through the plasma membrane on their own. When the molecules are too large, insoluble, oppositely flowing to the natural diffusion. The answer will be all of the above. What is facilitated diffusion ? Facilitated diffusion is the diffusion in which molecules can not pass through the membrane on their own. Facilitated diffusion is helped by some ions and active transport ions along with various transporters channels such as glucose transport is facilitated by GLUT transporter channel. The natural diffusion is the flow of molecules from the higher concentration to lower concentration. If the molecules move oppositely to the phenomenon in which natural diffusion is taking place in this condition it is facilitated diffusion. Learn more about facilitated diffusion at : https://brainly.com/question/15873457#SPJ2
Facilitated diffusion is necessary when B. the molecules are insoluble. Insoluble molecules need help to diffuse across membrane, this is also called passive transport.