Assertion:The resting membrane of the neuron exhibits polarity of charges
Reason:The outer surface of the axonal membrane possesses a negative charge while its inner surface becomes positively charged.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

C

Explanation

When a neuron is not conducting any impulse,i.e, resting the axonal membrane is comparatively more permeable to potassium ions`(K^(+))` and nearly impermeable to sodium ions `(Na^(+))`. Similarly, the membrane is impermeable to negatively charged proteins present in the axoplasm. Consequently, the axoplasm inside the axon contains high concentration of `K^(+)` and negatively charged proteins and low concentration of `Na^(+)`.These ionic gradients across the resting membrane are maintained by the active transport of ions by the soduim potassium pump which transpots `3 Na^(+))` outwords for `2K^(+))` into the cell. As a result, the outer surface of the axonal membrane possesses a positive charge while is inner surface becomes negatively charged and therefore is polariesed.