Question

In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed would drive _____.

• A. K⁺ into the cell
• B. K⁺ and Na⁺ out of the cell
• C. Na⁺ into the cell
• D. Na⁺ out of the cell.

Answer 1

The correct option is (C):

Explanation of the correct option:

1. ​In the resting nerve fibre, in the external medium (tissue fluid), sodium ions (Na+) predominate, whereas within the fibre (intracellular fluid) potassium ions (K+) predominate.
   
2. Due to different concentrations of ions on the two sides of the membrane, sodium ions tend to passively diffuse into the nerve fibre.
   
3. Potassium ions tend to diffuse out of the nerve fibre down their electrochemical gradients.

Final Answer: In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed would drive Na+ into the cell.