Active Transport Low To High __link__ [ EASY ]

Think of passive transport like a ball rolling down a hill; it happens naturally without effort. Active transport is like pushing that same ball back up the hill; it requires constant work and energy. Primary vs. Secondary Active Transport

In the world of physics and biology, molecules naturally want to spread out. This is known as moving down a concentration gradient. Active transport defies this natural flow. Because it moves substances "uphill"—from low to high concentration—the cell must expend metabolic energy, typically in the form of Adenosine Triphosphate (ATP). active transport low to high