A researcher is studying facilitated diffusion of a novel solute 'X' across a cell membrane using an artificial lipid bilayer system. They observe that increasing the concentration of X on one side of the membrane increases the rate of transport, but only up to a certain point. Beyond this point, further increases in X concentration do not affect the transport rate. Which of the following BEST explains this observation?
The membrane has reached its maximum permeability for X.
The solute X is being actively transported at higher concentrations.
Saturation of the carrier proteins
The solute X is inhibiting its own transport through feedback regulation.
Related Questions
    Select the wrong statement regarding membrane channels
    They are proteins
They are usually gated, i.e., may be open or closed
    All ions pass through the same type of channel
    They form a huge pore in the outer membrane of plastids, mitochondria and some bacteria
