Final answer:
The addition of Na+ leak channels to a membrane with only K+ leak channels would likely make the resting membrane potential less negative. Given the typical RMP is -70 mV, the addition of Na+ channels would result in an RMP of -70 mV. option a.
Step-by-step explanation:
The student's question pertains to predicting the resting membrane potential (RMP) when Na+ leak channels are added to a membrane that originally has only K+ leak channels and an RMP of -90 mV. In the context of a membrane with only potassium leak channels, the negative RMP is mainly because of the outward movement of K+, as potassium ions are at a higher concentration inside the cell compared to the outside, which leads to a net loss of positive charges and thus a negative potential inside.
When Na+ leak channels are added, sodium ions, which are at a higher concentration outside of the cell, can enter the cell. This inward movement of Na+ makes the inside of the cell less negative, leading to depolarization. Therefore, the addition of Na+ leak channels to a membrane would likely result in a less negative RMP. Given that the typical resting membrane potential is around -70 mV, and the addition of Na+ channels will lead to a partial depolarization, the predicted resting membrane potential after the addition of Na+ leak channels would likely be option (a) -70 mV.