<P> Unlike passive transport , which uses the kinetic energy and natural entropy of molecules moving down a gradient , active transport uses cellular energy to move them against a gradient , polar repulsion , or other resistance . Active transport is usually associated with accumulating high concentrations of molecules that the cell needs , such as ions , glucose and amino acids . If the process uses chemical energy , such as from adenosine triphosphate ( ATP ) , it is termed primary active transport . Secondary active transport involves the use of an electrochemical gradient . Examples of active transport include the uptake of glucose in the intestines in humans and the uptake of mineral ions into root hair cells of plants . </P>
active transport performs which function in a cell
usually associated with accumulating high concentrations of molecules that the cell needs , such as ions , glucose and amino acids