Neurons are excitable cells because their membranes are in a –

• Depolarised state

• Polarized state

• Repolarized state

• None of the above is correct

Ion channels present on neural membrane are –

• Impermeable

• Semipermeable

• Selective permeable

• Fully permeable

A polarized neuron is said to be in –

• Action potential

• Spike potential

• Resting potential

• None of these

When a neuron is not conducting any impulse i.e. resting, the axonal membrane is –

• Comparatively more permeable to K⁺ and impermeable (nearly impermeable) to Na⁺

• Impermeable to negatively charged proteins present in the axoplasm

• Both a and b

• More permeable to Na+ ions than K+ ion.

What generally maintains the electrical charge across the neuronal membrane?

• Na⁺ - K⁺ pump

• Action potential

• resting potential

• Voltage - gated channels

Na⁺ - K⁺ pump

I. No needs energy (ATP) to work

II. Expels 3 Na⁺ for every 2K+ ions imported

III. Works against a concentration gradient

IV. Maintains resting potential

• All are correct

• Only II and III are correct

• Only I and III are correct

• Only I is incorrect

During depolarization of the neuronal membrane –

• Na⁺ ions rapidly move to the inside of the cell

• Na⁺ ions rapidly move to the outside of the cell

• K⁺ ions rapidly move to the outside of the cell

• K⁺ ions rapidly move to the outside of the cell

A segment of neuronal membrane showing action potential is said to be –

• Polarized

• Depolarized

• Repolarized

• None of the above

The electrical potential difference across the depolarized membrane is called –

• Action potential

• Resting potential

• Water potential

• Solute potential

Which of the following diagram illustrates the distribution of Na⁺ and K^{+ i}ons in a section of non-myelinated axon which is at resting potential?

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