Final answer:
Calcium, hydrogen, and Na+/K+ pumps use active transport, a mechanism that moves ions against their concentration gradients, requiring energy from ATP. The sodium-potassium pump exemplifies this by exchanging sodium and potassium ions across the cell membrane.
Step-by-step explanation:
Calcium, hydrogen, and Na+/K+ pumps all work using active transport mechanisms. The primary active transport moves ions across a membrane and creates a difference in charge across that membrane. It uses ATP to move substances into and out of the cell against their concentration gradients, often with the help of carrier proteins that change shape to transport the ions. The sodium-potassium pump is a key example, using energy from ATP to move three sodium ions out of the cell and two potassium ions into the cell.
Additionally, this active transport system can be linked with passive transport systems in a process called secondary active transport. For instance, after sodium ions are pumped out of the cell, creating a high concentration of sodium outside, the cell can then open a passive sodium channel to let sodium ions flow back in down their concentration gradient. Other examples of active transport systems include Ca²+ ATPase and H+ ATPase, which transport calcium and hydrogen ions respectively.