4.Active transport Carrier protein mediated movement up the gradient This process differs from facilitated diffusion in two crucial aspects: Active transport maintains the gradients for potassium, sodium,calcium,and other ions across the cell membrane.Always moves solutes up a concentration or electrochemical gradient; Active transport couples the movement of substances against gradients to ATP hydrolysis.i.e always requires the input of energy. This document is produced by trial version of Print2Flash.Visit www.print2flash.com for more information