Question

30/40
which process requires atp?
diffusion of k⁺
opening of voltage-gated na⁺ channels
active transport by na⁺/k⁺ pump
diffusion of na⁺

Explanation:

To determine which process requires ATP, we analyze each option:

• Diffusion (of \( \text{K}^+ \) or \( \text{Na}^+ \)) is passive transport (moves down concentration gradient), so no ATP.
• Opening voltage - gated \( \text{Na}^+ \) channels is a conformational change due to voltage, not ATP - driven.
• The \( \text{Na}^+/\text{K}^+ \) pump is active transport, which moves ions against concentration gradients. Active transport requires energy, and the \( \text{Na}^+/\text{K}^+ \) pump uses ATP to pump \( 3\text{Na}^+ \) out and \( 2\text{K}^+ \) in per cycle.

Answer:

C. Active transport by \( \text{Na}^+/\text{K}^+ \) pump