Question

the sodium-potassium pump uses atp to move sodium and potassium ions across the plasma membrane. this statement describes ______.

○ exocytosis

○ primary active transport

○ simple diffusion

○ secondary active transport

○ facilitated diffusion

Explanation:

• Exocytosis is the process of vesicles fusing with the membrane to release substances, not ion transport via ATP, so this is incorrect.
• Primary active transport directly uses ATP to move substances against their concentration gradient. The sodium - potassium pump uses ATP to move Na⁺ and K⁺, so this fits.
• Simple diffusion is the passive movement of substances down their concentration gradient without energy or a protein, so this is incorrect.
• Secondary active transport uses the energy from an ion gradient (created by primary active transport) to move other substances, not direct ATP use for the ion movement in question, so this is incorrect.
• Facilitated diffusion is passive transport (uses a protein but no energy) down the concentration gradient, so this is incorrect.

Answer:

B. primary active transport