Okay, stop right there. If they’re so similar, what makes them different? It’s the energy bill. Facilitated diffusion is the lazy friend who never pays for gas—it uses zero energy. Active transport is the chauffeur who revs the engine, burning cellular fuel called ATP (your body’s energy currency).
Imagine you’re at a crowded concert. If you walk through the exit door with the crowd (high to low pressure), that’s facilitated diffusion. Easy, free, and no shoving. But if you need to push your way backstage against the flood of fans (low to high pressure), that’s active transport. You’ll need a security guard—and a whole lot of energy.
The common thread? Both are about moving stuff across a barrier. One is a leisurely float downstream; the other is a determined uphill climb.
Cellular Concentration Gradient
