In a chemical reaction, a reactant binds to an enzyme at a region known as the
a. catalyst.
b. product.
c. substrate.
d. active site.

Idon't know how to do this but maybe ask your mom or dad

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.