The graph shows rates of simple diffusion and facilitated diffusion, of substance X across a cell surface membrane, as the concentration of substance X increases.
Why does the rate of facilitated diffusion level off whereas the rate of simple diffusion does not?
Facilitated diffusion is limited by the number of protein channels in the membrane.
2 )
Facilitated diffusion is limited by the number of protein pumps in the membrane.
3 )
Facilitated diffusion requires ATP which will eventually be used up.
4 )
Only facilitated diffusion is affected by the kinetic energy of the molecules that are diffusing.
