Question

for normal nerve transmission in mammals, nerve cells maintain specific concentrations of potassium (k+) and sodium (na+) ions. concentrations of na+ ions are normally higher outside the cell and lower inside the cell, while k+ ions are normally lower outside the cell and higher inside the cell. however, cell membranes are impermeable to na+ and k+ ions. the diagram shows the relative concentrations of ions in solution inside and outside the cell. relative concentrations of ions on each side of the cell membrane outside k+ lower na+ higher inside k+ higher na+ lower which process describes how a nerve cell maintains homeostasis in regards to the na+ and k+ ion concentrations? a by converting the sodium ions present inside the cell into potassium ions b by blocking both types of ions from moving into or out of the cell membrane c by transporting both types of ions through protein pumps within the cell membrane d by producing more potassium ions inside the cell and eliminating sodium ions as waste

Explanation:

• Option A: Sodium ions cannot be converted into potassium ions. This is not a biological process for maintaining ion concentrations.
• Option B: While cell membranes are impermeable to \(Na^{+}\) and \(K^{+}\) ions under normal circumstances, just blocking them without active transport would not maintain the concentration gradients. Passive diffusion would eventually equalize concentrations if there was no active mechanism.
• Option C: The sodium - potassium pump (a protein pump in the cell membrane) actively transports \(Na^{+}\) out of the cell (against its concentration gradient, since \(Na^{+}\) is higher outside) and \(K^{+}\) into the cell (against its concentration gradient, since \(K^{+}\) is higher inside). This active transport (using ATP) maintains the homeostatic ion concentrations.
• Option D: Cells do not produce potassium ions from scratch. They take up potassium ions from the extracellular environment, and eliminating sodium ions as waste in the described way (without a proper transport mechanism) is not how the concentration gradients are maintained.

Answer:

C. by transporting both types of ions through protein pumps within the cell membrane