Multiple Choice The endocrine and muscular systems interact to absorb nutrients when the-
A. tongue and saliva break down food.
B. stomach villi and blood distribute food.
C. jawbone and muscles grind down food.
D. esophagus and stomach transport the food.

1. an enzyme is considered a(n) because it speeds up a chemical reaction without being used up.2. in a catalyzed reaction, a reactant is often called a(n) . an enzyme is specific because the shape of its matches only particular reactants.4. an enzyme speeds up reactions by lowering the . the between an active site and its substrate often strains bonds and the reaction proceed.6. a( , which is often a vitamin, binds to an enzyme and plays a role in catalysis.7. high temperatures or changes in ph can an enzyme, causing it to lose its shape and biological activity.