Question

What is a substrate?

Answer 1

an underlying substance or layer.
the surface or material on or from which an organism lives, grows, or obtains its nourishment.
"brachiopods attached to the substrate by a stalk"
the substance on which an enzyme acts.

Answer 2

A substrate is a molecule acted upon by an enzyme. A substrate is loaded into the active site of the enzyme, or the place that allows weak bonds to be formed between the two molecules. An enzyme substrate complexis formed, and the forces exerted on the substrate by the enzyme cause it to react, and become the product of the intended reaction.