The substance on which the enzyme acts is called the chemical. A. Substrate
B. Complex
C. Catalyst

the answer is A

Explanation:

it is substrates because ,Enzymes are specialized proteins that catalyze or speed up chemical reactions within cells. The substance upon which an enzyme acts is called a substrate. Substrates are small molecules.

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

smooth muscle is composed of involuntary muscles found within the walls of organs and structures such as the esophagus, stomach, intestines, and blood vessels. those muscles push materials like food or blood through organs. unlike skeletal muscle, smooth muscle can never be under your control.