Galen Anatomy and Physiology (A&P) 1 Theory Exam 2 Practice

Carrier-mediated transport uses a specific carrier protein that binds the substance and shuttles it across the membrane. When this movement requires energy to push the substance against its concentration or electrochemical gradient, it becomes active transport. This distinguishes it from diffusion or osmosis, which do not rely on carrier proteins, and from endocytosis, which is vesicle-based. So, in contexts where energy is needed to move substances uphill, carrier-mediated transport is a form of active transport.