The movement of ions across a membrane is dependent on both the membrane potenti

Question

The movement of ions across a membrane is dependent on both the membrane potential and the ion’s concentration gradient. This combination of electrical force and ion concentration is known as the electrochemical gradient. Which of the following statements about membrane potential is false?

a. Membrane potential is the result of unequal distribution of cations and anions on opposite sides of the membrane.

b. The charge of the cytoplasmic side of the membrane is negative relative to the extracellular side of the membrane.

c. Membrane potential plays a role in selective permeability because ions cannot enter the cell without being actively transported inside.

d. Membrane potential is maintained by ion pumps.

Explanation / Answer

a) True: Membrane potential is the result of unequal distribution of cations and anions on opposite sides of the membrane

Explanation: The membrane potential is determined by the uneven distribution of ions (charged particles) between the inside and the outside the cell. Other factor which involve is the differential permeability of membrane to different types of ions.

b) True: The charge of the cytoplasmic side of the membrane is negative relative to the extracellular side of the membrane

Explanation: The charge inside the cell is negative (-70) volt, called resting potential, because there are relatively more sodium ions outside the cell and more potassium ions inside that cell.

c) False: Membrane potential plays a role in selective permeability because ions cannot enter the cell without being actively transported inside

Explanation: Ions in the cell may be transported passively without the use of metabolic energy by ion channels.

d) True: Membrane potential is maintained by ion pumps.

Explanation: Membrane potential is maintained by the Na+/K+ pump.

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