Question

Which is true of an action potential?

a. The plasma membrane is impermeable to Na+ and K+ ions.
b. Na+ ions move extracellularly.
c. The charges become equal on the outside and inside of the plasma membrane.
f. The outside of the plasma membrane is negatively charged, and the inside is positively charged.

Answer 1

The truth about an action potential is that during depolarization, the plasma membrane's inside becomes positively charged due to Na+ ions entering, and during repolarization, the membrane returns to a negatively charged state internally as K+ ions exit option a is correct.

Step-by-step explanation:

The true statement about an action potential is that the outside of the plasma membrane is negatively charged, and the inside is positively charged. An action potential begins with depolarization, where a stimulus causes the membrane to become permeable to Na+ ions, allowing them to rush into the cell.

This influx of Na+ causes the inside of the membrane to become temporarily positive relative to the outside.

Following depolarization, repolarization occurs as the membrane becomes impermeable to Na+ and K+ ions move from high to low concentration, restoring the negative internal charge.

The sodium-potassium pump then activates to maintain the resting membrane potential by actively transporting ions against their concentration gradients, using ATP in the process.

This sequence of ion movement and electrical charge changes is what propels the action potential down the axon.