Final answer:
The resting membrane potential is due to both the uneven distribution of Na+ and K+ ions across the cell membrane and the differential permeability of the cell membrane to these ions, with the Na+/K+ pump and leakage channels helping to maintain this potential.
Step-by-step explanation:
The resting membrane potential is primarily established by the uneven distribution of ions across the cell membrane and by the differences in membrane permeability to Na+ and K+ ions. The key players in creating and maintaining the resting membrane potential are the Na+/K+ pump and the ion leakage channels. The pump actively transports K+ ions into the cell and Na+ ions out of the cell, consuming ATP in the process. This active transport is crucial for maintaining high concentrations of K+ inside and Na+ outside the cell. Additionally, the cell membrane's semi-permeability allows K+ to move out more readily than Na+ can enter, which contributes to the membrane potential.
Ion leakage channels play a role in allowing K+ to leak out of the cell and Na+ to trickle in, but the activity of the Na+/K+ pump compensates for this leakage. This dynamic ensures that the interior of a neuron remains negatively charged relative to the outside, which is largely due to the concentration gradients and the selective permeability of the membrane. The negative charge within a neuron at rest is approximately -70 mV, but this figure can vary among different cell types and species.
Therefore, the correct answer to the student's question would be D. uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+.