[Campbell Biology P.838] If a specific inhibitor completely blocks the function of the ATP-d... | Practice Question

If a specific inhibitor completely blocks the function of the ATP-dependent proton pump Figure 36.6a in a plant cell, what would be the most immediate and significant effect on the cell's membrane potential?

  • A: The membrane potential would become more negative, as H+ ions would accumulate inside the cell.
  • B: The membrane potential would become less negative (more positive or depolarized) because the active pumping of positive H+ ions out of the cell would cease.
  • C: The membrane potential would remain unchanged, as other transport proteins would compensate.
  • D: The cell would rapidly swell and burst due to uncontrolled water influx.

Explanation

The ATP-dependent proton pump actively pumps positive H+ ions out of the cell. This outward movement of positive charges makes the inside of the cell relatively negative, establishing the membrane potential. If this pump is inhibited, the active removal of positive charges ceases, leading to a reduction in the negativity of the interior, or a depolarization of the membrane potential making it less negative or more positive .