NaKATPase is considered to be an electrogenic pump because i

Na⁺/K⁺–ATPase is considered to be an electrogenic pump because

it contributes to the negativity of the resting membrane potential.

the sodium ions are negatively charged.

it exhibits low permeability.

both it contributes to the negativity of the resting membrane potential and the sodium ions are negatively charged.

all of these choices

When a depolarizing graded potential makes the axon membrane depolarize to threshold,

ligand-gated Ca⁺² channels close rapidly.

voltage-gated Ca⁺² channels open rapidly.

ligand-gated Na⁺ channels close rapidly.

voltage-gated Na⁺ channels open rapidly.

During this period, a second action potential can only be initiated by a larger than normal stimulus

Latent period

Absolute refractory period

Relative refractory period

All of these choices

Solution

Na+/K+-ATPase is considered to be an electrogenic pump because it transports three Na+ ions outside the cell and two K+ ions into the cytoplasm of the cell in each cycle of transport thus the option: it contributes to the negativity of the resting membrane potential is true

When a depolarizing graded potential makes the axon membrane depolarize to threshold: Voltage-gated Na+ channels open rapidly is correct option as the positively charged Na+ ions depolarize.

During this period, a second action potential can only be initiated by a larger than normal stimulus: Relative refractory period is the correct option