Final answer:
A neuron at rest maintains an electrochemical gradient across its membrane to facilitate the transmission of electrical signals, which is essential for neuron function.
Step-by-step explanation:
A neuron at rest (at resting potential) has a charge of about -70 millivolts and is considered to be polarized because it maintains an electrochemical gradient across the cell membrane. This gradient is crucial for the rapid transmission of electrical signals when the neuron becomes active. The resting membrane potential is created by the selective permeability of the neuron's membrane, primarily to potassium and sodium ions, and the action of the sodium-potassium pumps, which exchange three Na+ ions from inside to outside of the neuron for two K+ ions from outside to inside. These pumps use a significant amount of ATP to maintain this gradient, and the higher internal concentration of K+ ions compared to Na+ ions contributes to the net negative charge inside the cell.