This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
For sodium-potassium pump, the coupling ratio is 
Select and explain. 
A. 1:01, B. 2:03, C. 3:02, D. 1:04
C: 3:02
Answer: C: 3:02 
Explanation: Na, K ATPase catalyzes the hydrolysis of ATP to adenosine diphosphate (ADP) and uses the energy to extrude three Na+ from the cell and take two K+ into the cell for each molecule of ATP hydrolyzed. It is an electrogenic pump in that it moves three positive charges out of the cell for each two that it moves in, and it is therefore said to have a coupling ratio of 3:2.