Why does flowing water deposit the largest particles first

Deposition by Water

Flowing water slows down when it reaches flatter land. ... The water starts dropping the particles it was carrying. As the water slows, it drops the largest particles first. The smallest particles settle last.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme