Question

Fill in the blanks by choosing the most suitable option:
A resting axonal membrane is comparatively more permeable to ........... and nealy impermeable to.......

• A. $N{a}^{+}$ ions and $K^{+}$ ions
• B. $K^{+}$ ions and $N{a}^{+}$ ions
• C. $C{a}^{+}$ ions and $N{a}^{+}$ ions
• D. $K^{+}$ ions and $C{a}^{+}$ ions

Answer 1

Answer: (B)

In resting axonal membrane, $K^{+}$ ion channels are opened as they are slow workers or lazy channels. Their time of closing is more as compared to $N{a}^{+}$ channels which are closed as soon as the impulse passes off. Due to the presence of opened $K^{+}$ channels, the permeability of $K^{+}$ is more and as the $N{a}^{+}$ channels are closed the membrane is impermeable to $N{a}^{+}$ .