Generally, a gradient is how much something changes when that something moves from one region to another. Therefore, concentration gradient refers to how much the concentration changes when something moves from one region to another. In biology, concentration gradient refers to the gradual change in a solute’s concentration in a solution as a function of the distance the molecules traverse. The concentration gradient is important because it enables us to understand how particles move in random motion in a solution. A concentration gradient ceases to exist when there is no net movement.