Question

the electrical gradient, created by the outflow of more positive sodium ions than the inflow of positive potassium ions, is used by neurons and muscles to create the action potentials responsible for nervous system function and muscular contraction. the chemical gradient, which is created by the higher concentration of sodium ions in the extracellular space as opposed to the cytoplasm, results in the tendency of sodium ions to flow down their concentration gradient and back into the cytoplasm through other transmembrane proteins. what is the net effect of the sodium - potassium pump? a the sodium - potassium pump uses atp to maintain a zero charge balance between the internal and external environments of the cell. b the sodium - potassium pump facilitates the movement of sodium and potassium ions across the membrane in a manner that keeps the concentration gradient at equilibrium. c the sodium - potassium pump uses atp to pump three potassium ions out of the cell for every three sodium ions pumped into the cell, thus maintaining neutral conditions. d the sodium - potassium pump uses atp to pump two potassium ions into the cell for every three sodium

Explanation:

The sodium - potassium pump is an active - transport mechanism. It uses ATP to move three sodium ions out of the cell and two potassium ions into the cell. This helps maintain the electrochemical and concentration gradients essential for nerve and muscle function. Option A is incorrect as it doesn't maintain a zero - charge balance. Option C has the wrong ion movement ratio. Option B is wrong as it doesn't describe the correct ion movement and the role in maintaining gradients accurately.

Answer:

D. The sodium - potassium pump uses ATP to pump two potassium ions into the cell for every three sodium ions pumped out of the cell, maintaining the electrochemical and concentration gradients.