Active transport is the movement of ions or molecules across a cell membrane from a region of lower concentration to a region of higher concentration, which requires energy input.

Types of Active Transport:

1. • Primary Active Transport: Direct use of energy (typically from ATP hydrolysis) to transport molecules. Example: The sodium-potassium pump (Na⁺/K⁺-ATPase).

   • Secondary Active Transport (Cotransport): Uses the energy from the electrochemical gradient created by primary active transport to move other substances. Example: Sodium-glucose cotransporter (SGLT).