[Campbell Biology P.186] According to the text, what is the primary cause of the membrane po... | Practice Question

According to the text, what is the primary cause of the membrane potential across a cell's plasma membrane?

  • A: The equal distribution of anions and cations on both sides of the membrane.
  • B: The negative charge of the extracellular side relative to the cytoplasmic side.
  • C: The separation of opposite charges due to an unequal distribution of ions across the membrane.
  • D: The spontaneous diffusion of hydrophobic molecules across the lipid bilayer.

Explanation

The text clearly states: 'Voltage is electrical potential energy ... a separation of opposite charges. The cytoplasmic side of the membrane is negative in charge relative to the extracellular side because of an unequal distribution of anions and cations on the two sides.' This directly points to the unequal distribution and resulting charge separation as the cause.