Which of the following is FALSE regarding the membrane potential?
A) The resting membrane potential is maintained by solely by passive transport processes.
B) In their resting state, all body cells exhibit a resting membrane potential.
C) The resting membrane potential is determined mainly by the concentration gradients and differential permeability of the plasma membrane to K+ and Na+ions.
D) The resting membrane potential occurs due to active transport of ions across the membrane due to the sodium-potassium pump.
The Correct Answer and Explanation is:
The correct answer is A) The resting membrane potential is maintained solely by passive transport processes.
Explanation
The resting membrane potential is the electrical potential difference across the plasma membrane of a cell when it is not actively sending signals, typically around -70 mV in many cells. This potential is crucial for various cellular functions, including signal transmission in neurons and muscle contraction.
A) The resting membrane potential is maintained solely by passive transport processes. This statement is false. While passive transport processes (like diffusion) contribute to the resting membrane potential, the sodium-potassium pump (Na+/K+ ATPase), which actively transports sodium out of the cell and potassium into the cell, plays a crucial role in maintaining this potential. The pump moves three sodium ions out for every two potassium ions it brings in, creating a net negative charge inside the cell relative to the outside, which is essential for maintaining the resting membrane potential.
B) In their resting state, all body cells exhibit a resting membrane potential. This statement is true. Most body cells have a resting membrane potential, which is vital for their function.
C) The resting membrane potential is determined mainly by the concentration gradients and differential permeability of the plasma membrane to K+ and Na+ ions. This statement is also true. The membrane is more permeable to potassium ions than to sodium ions at rest, which largely determines the resting potential. The high concentration of potassium ions inside the cell and the lower concentration outside creates a concentration gradient that influences the resting membrane potential.
D) The resting membrane potential occurs due to active transport of ions across the membrane due to the sodium-potassium pump. This statement is true. The sodium-potassium pump’s active transport of ions is essential for establishing and maintaining the resting membrane potential, despite the fact that some aspects of the resting potential are influenced by passive processes.
In summary, while passive transport plays a role in creating the resting membrane potential, it is not the sole mechanism; the active transport of ions by the sodium-potassium pump is essential for this process.