Substrate is the term given to the reactant in an enzyme-catalyzed reaction. Which of the following statements accurately describe/s substrates in enzyme-catalyzed reactions? (Select all that apply)
I. Substrates bind to the active site of an enzyme, forming an enzyme-substrate complex.
II. Substrates are permanently altered by the enzyme and cannot be reused in subsequent reactions since they remain bound to it.
III. Substrate binding to an enzyme is highly specific, often compared to a "lock and key" mechanism.
IV. The rate of the reaction increases as the substrate concentration increases until the enzyme is saturated.

• A. I and III
• B. III and IV
• C. I, III, and IV
• D. I, II, and IV

Answer: (C)