* Glucose: Active transport is crucial for moving glucose across cell membranes, particularly in the small intestine and kidneys. This is because the concentration of glucose is often higher inside the cell than outside, requiring energy to move it against its concentration gradient.
* Sodium Ions (Na+): The sodium-potassium pump is a classic example of active transport. It uses energy to pump sodium ions out of the cell and potassium ions into the cell, maintaining the electrochemical gradient that is essential for nerve impulse transmission, muscle contraction, and other vital processes.
