Questions: Part D Which of the following is the driving force for the sodium-potassium pump? a concentration gradient an electrical gradient ATP hydrolysis a hydrostatic pressure gradient

The answer is the third one: ATP hydrolysis.

Explanation for each option:

1. A concentration gradient: This is incorrect. While concentration gradients are involved in the movement of ions across membranes, the sodium-potassium pump specifically uses energy to move ions against their concentration gradients.

2. An electrical gradient: This is incorrect. Although electrical gradients can influence ion movement, the sodium-potassium pump actively transports ions against both concentration and electrical gradients, requiring energy input.

3. ATP hydrolysis: This is correct. The sodium-potassium pump is an active transport mechanism that uses energy derived from the hydrolysis of ATP to move sodium and potassium ions across the cell membrane against their respective gradients.

4. A hydrostatic pressure gradient: This is incorrect. Hydrostatic pressure gradients are not involved in the function of the sodium-potassium pump.

In summary, the driving force for the sodium-potassium pump is ATP hydrolysis, which provides the necessary energy to transport ions against their gradients.