Concept 8.4: Active transport usesenergy to move solutes against theirgradients• Facilitated diffusion is still passive because the solutemoves down its concentration gradient, and thetransport requires no energy.• Some transport proteins, however, can move solutesagainst their concentration gradients.– Called active transport– requires energy, usually in the form of ATP.– Active transport is performed by specific proteinsembedded in the membranes.