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In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed, would drive :-
A
$K^+$ and $Na^+$ out of the cell
B
$Na^+$ into the cell
C
$Na^+$ out of the cell
D
$K^+$ into the cell
Detailed Solution
At rest, the sodium-potassium pump maintains a high concentration of $Na^+$ outside the axon and a high concentration of $K^+$ inside.
Diffusion always moves an ion from higher to lower concentration.
So $Na^+$, being more concentrated outside, would diffuse into the cell.
$K^+$, being more concentrated inside, would diffuse out of the cell (not into it).
Among the given choices, the correct one is that diffusion would drive $Na^+$ into the cell. (At rest the membrane is far less permeable to $Na^+$, which is why this does not happen until an action potential opens sodium channels.)
Diffusion always moves an ion from higher to lower concentration.
So $Na^+$, being more concentrated outside, would diffuse into the cell.
$K^+$, being more concentrated inside, would diffuse out of the cell (not into it).
Among the given choices, the correct one is that diffusion would drive $Na^+$ into the cell. (At rest the membrane is far less permeable to $Na^+$, which is why this does not happen until an action potential opens sodium channels.)