For a cell to survive, it can’t just go with the flow. While passive transport allows molecules to move "downhill" from high to low concentration, cells often need to pull molecules "uphill"—against their concentration gradient. This requires .
The distinction between and secondary active transport lies entirely in their power source: one burns fuel directly, while the other harvests energy from a pre-built "dam." 1. Primary Active Transport: The Direct Powerhouse secondary active transport vs primary
