Question

multiple - choice question
why does a cell need to use membrane pumps?
because the cell needs to have all molecules be in equal concentrations inside and outside the membrane
because sometimes \equilibrium\ is not what the cell needs

Explanation:

Cells use membrane pumps to actively transport substances against their concentration gradients. Equilibrium in terms of equal concentrations of all molecules inside and outside the cell is not always beneficial or necessary for cell - function. Membrane pumps help maintain specific ion and molecule concentrations required for processes like nerve impulse transmission, muscle contraction, and maintaining cell volume.

Answer:

because sometimes "equilibrium" is not what the cell needs