At rest, a cell membrane is said to be
a. polarized
b. unpolarized
c. depolarized
d. repolarized

a. polarized

Explanation:

The whole living cell and in particular the nerve cells show electric potential difference between the inner and outer faces of their cell membrane.

The resting potential of a cell refers to the difference in electrical potential that the inner and outer faces in the membrane of a neuron that is not transmitting nerve impulses. The resting potential value is around -70mV (milliVolts). The negative sign indicates that the interior of the cell is negative relative to the exterior.

The existence of the resting potential is mainly due to the difference in concentration of sodium (Na +) and potassium (K +) ions inside and outside the cell. This difference is maintained by a mechanism of active ion pumping through cell membranes, in which sodium is forced out of the cell and potassium in.

At rest, the alternation between passive and active ion transport occurs. There is passive input of sodium (Na +) ions, which are subsequently actively expelled, while potassium (K +) ions enter actively. Then K + passes passively from the cell, making the external medium positive relative to the internal medium. With this, the cell becomes polarized.

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