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SECTION
ENZYMES
2.5
Section Quiz
Choose the letter of the best answer.
1. Which phrase best describes the effect of a catalyst on a chemical reaction?
a. increases the temperature
b. increases the volume of reactants
c. decreases the reaction rate
d. decreases the activation energy
2. Which statement best describes the graph shown?
CHAPTER 2
Chemistry of Life
Energy
Original reaction
Reaction B
products
reactants
Reaction progress
FIG. 2.5.1
a. More energy is released by the original reaction.
b. Less energy is needed to start reaction B.
c. The original reaction is catalyzed.
d. Reaction B occurs at a slower rate.
Copyright © McDougal Littell/Houghton Mifflin Company.
3. Enzymes affect chemical reactions in living organisms by
a. changing the direction of a reaction.
b. breaking down molecules into starch.
c. increasing the temperature range.
d. weakening bonds in reactants.
4. The specific reactants that an enzyme acts on are called
a. catalysts
c. substrates.
b. proteins.
d. amino acids.
5. Changes in temperature and pH can decrease an enzyme’s activity by breaking
a. hydrogen bonds
c. amino acids
b. peptide bonds
d. sulfur–sulfur bonds
Assessment Book
McDougal Littell Biology
Section Quiz
29