Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What are the primary functions of the sodium-potassium pump in a cell?

1. Formation of proteins

2. Moving ions across the membrane

3. Digestion of nutrients

4. Synthesis of ATP

The correct answer is: Moving ions across the membrane

The primary functions of the sodium-potassium pump involve the active transport of sodium and potassium ions across the cell membrane, which is crucial for maintaining the electrochemical gradient that is essential for various cellular processes. This pump moves sodium ions out of the cell and potassium ions into the cell, typically transporting three sodium ions out for every two potassium ions moved in. This action is vital for maintaining the resting membrane potential, playing a key role in nerve impulse transmission, muscle contraction, and overall cellular homeostasis. The movement of ions by the sodium-potassium pump is an example of active transport, as it requires energy in the form of ATP to move ions against their concentration gradients. By maintaining the appropriate balance of these ions, the pump contributes to essential physiological processes such as cell signaling and volume regulation.