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
Certain integral membrane proteins facilitate the diffusion of molecules across the membrane without directly binding to the transported molecule. These proteins create a continuous aqueous pathway through the lipid bilayer. Which of the following is the BEST example of such facilitated diffusion?
GLUT transporters moving glucose
Sodium-potassium pump maintaining ion gradients
Aquaporins transporting water
Chloride channels gated by voltage
    What is mandatory in the process of facilitated diffusion?
    Presence of concentration gradient
A carrier protein
A hydrophilic moeity
All of the above
Facilitated diffusion is different from simple diffusion because it:
Moves molecules against the concentration gradient
Uses carrier proteins
Requires ATP
Occurs only in plant cells
Which of the following feature is not related to facilitated diffusion?
Transport protein required
Along the concentration gradient
Require the energy in the form of ATP
Can respond to inhibitors
Facilitated diffusion differs from simple diffusion in that it:
Requires ATP
Moves substances against their concentration gradient
Requires membrane proteins
Occurs only in plant cells
    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
Facilitated diffusion does not require/show
Special membrane proteins
Saturation of transport
ATP energy
Selective nature
Facilitated diffusion involves?
Downhill transport
Without expenditure of energy
Involvement of proteins
All
    Which of the following pair is selective and specific mode of transport?
    Passive transport and active transport
    Passive transport and facilitated diffusion
Facilitated diffusion and active transport
    Simple diffusion and facilitated diffusion
Facilitated diffusion does not require/show
Special membrane proteins
Saturation of transport
ATP energy
Selective nature
