[Campbell Biology P.1119] Why is the significant net outflow of K+ through open potassium cha... | Practice Question

Why is the significant net outflow of K+ through open potassium channels leak channels crucial for establishing the resting membrane potential?

  • A: It directly causes the influx of Na+ ions, balancing the charge.
  • B: K+ outflow creates a net negative charge inside the cell because the membrane is weakly permeable to other anions.
  • C: It consumes ATP to maintain the K+ gradient.
  • D: It prevents the accumulation of large anions inside the cell.

Explanation

The text explains that while the sodium-potassium pump establishes the ion gradients, the large net outflow of K+ through many open potassium leak channels is crucial. Because the membrane is only 'weakly permeable to chloride and other anions' which are negatively charged and trapped inside , this outflow of K+ positive charge results in a net negative charge inside the cell, creating the resting potential.