9. all of the following are elements except

a. sugar

b. aluminum

c. hydrogen

d. iron

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?

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.

Describe the structure of amino acid, including what makes amino acids different from eachother