Question

For a cell at resting membrane potential, which is most accurate?

a) K+ leak channels are open
b) K+ should diffuse into the cell
c) Na+ should diffuse out of the cell
d) Only Na+ is actively transported
e) An efflux of K+ would cause depolarization

Answer 1

The most accurate statement for a cell at resting membrane potential is that K+ leak channels are open, allowing for the passive movement of K+ out of the cell which contributes to maintaining the resting potential at around -70 mV.

Step-by-step explanation:

For a cell at resting membrane potential, the most accurate statement is that K+ leak channels are open. The resting membrane potential is typically around -70 mV, maintained by a difference in concentration of Na+ and K+ ions inside and outside the cell. During this state, voltage-gated Na+ channels and most voltage-gated K+ channels are closed. However, K+ leak channels remain open, allowing K+ to slowly move out of the cell, while the Na+/K+ transporter, which actively pumps K+ ions into the cell and Na+ ions out of the cell, maintains the overall ion balance.

An efflux of K+ does not cause depolarization; instead, it helps maintain the resting potential. It is when Na+ rushes into the cell that depolarization occurs, moving the membrane potential toward zero. Therefore, Na+ ions diffusing into the cell and K+ ions moving out are critical processes in maintaining the resting membrane potential and enabling subsequent action potentials.