Question 1

At rest, the inside of a neuron's membrane is ______ relative to the outside:

Accepted Answer

Negatively charged. The resting membrane potential (~ −70 mV) keeps the axon interior negative relative to the outside.

Question 2

During the generation of an action potential, the membrane suddenly becomes permeable to ______ ions:

Accepted Answer

Sodium (Na⁺). Depolarisation occurs when Na⁺ channels open and Na⁺ rushes in, reversing the membrane polarity.

Question 3

The resting potential is maintained mainly by the ______, which pumps 3 Na⁺ out and 2 K⁺ in:

Accepted Answer

Sodium-potassium pump (Na⁺/K⁺ ATPase). The Na⁺/K⁺ ATPase keeps high K⁺ inside and high Na⁺ outside, maintaining the polarised resting state.

Question 4

The restoration of the resting potential after an action potential (repolarisation) is caused by the outflow of:

Accepted Answer

Potassium (K⁺) ions. Repolarisation occurs as K⁺ channels open and K⁺ flows out, restoring the negative interior.

Question 5

The all-or-none law of nerve impulses states that:

Accepted Answer

A stimulus above threshold produces a full-sized impulse; below threshold produces none. Once threshold is reached, the action potential is of a fixed magnitude regardless of further stimulus strength.

Question 6

At the peak of an action potential, the membrane potential becomes about ______, a state called:

Accepted Answer

+30 mV; depolarised (reversed polarity). At the action potential peak the potential reverses to about +30 mV (inside positive) — depolarisation.

Nerve Impulse & Membrane Potential — NEET Biology MCQs with Solutions

Questions with solutions