Which statement best describes what the density of an object represents?
Density is the mass of an object per unit of
length.
Density is the volume of an object of a
certain mass.
Density is the length of an object for a certain
mass.
Density is the amount of matter in a certain
volume.

Choose an equation that represents an enzyme-catalyzed reaction. (a) enzyme + substrate → enzyme-substrate complex (b) enzyme + substrate ←−→ enzyme + products (c) enzyme + substrate ←−→ enzyme-substrate complex → enzyme + products (d) enzyme + substrate ←−→ enzyme-substrate complex → enzyme-substrate complex + products