Lesson 3.3.13.3

3.3.13.3 Enzymes Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.13.3, Enzymes: 20 multiple choice questions for the AQA Chemistry (7405), Unit 3: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. To which class of biological macromolecules do all enzymes belong?

    • Carbohydrates
    • Proteins
    • Nucleic acids
    • Lipids

  2. What name is given to the specific region of an enzyme where the substrate binds?

    • Allosteric site
    • Binding pocket
    • Active site
    • Catalytic core

  3. Why can an enzyme active site usually only bind to one enantiomer of a substrate?

    • It is symmetrical
    • It is non-polar
    • It is denatured
    • It is stereospecific

  4. How does a competitive drug inhibitor prevent an enzyme from functioning?

    • Changes primary structure
    • Hydrolyses enzyme
    • Blocks active site
    • Breaks peptide bonds

  5. What do computers model to assist in designing enzyme inhibitor drugs?

    • Protein primary structure
    • Active site shape
    • Overall reaction rate
    • Substrate concentration

  6. Which model describes a substrate fitting precisely into an enzyme active site?

    • Collision theory
    • Induced fit
    • Fluid mosaic
    • Lock and key

  7. How do enzymes increase the rate of a biochemical reaction?

    • Lower activation energy
    • Increase activation energy
    • Increase kinetic energy
    • Lower enthalpy change

  8. Why can an enzyme active site generally only bind to one drug enantiomer?

    • Active site is chiral
    • Active site is ionic
    • Insoluble substrate
    • Achiral binding pockets

  9. What proportion of a racemic drug mixture is typically active at a stereospecific site?

    • 25%
    • 0%
    • 50%
    • 100%

  10. What happens to an enzyme active site when heated well above optimum temperature?

    • It becomes stereospecific
    • It freezes
    • It expands permanently
    • It denatures

  11. Which structural level of a protein forms the active site of an enzyme?

    • Tertiary structure
    • Secondary structure only
    • Primary structure only
    • Quaternary structure always

  12. How can competitive inhibition of an enzyme be overcome?

    • Decrease temperature
    • Increase substrate concentration
    • Increase inhibitor concentration
    • Decrease substrate concentration

  13. What type of drug blocks an enzyme active site to prevent substrate binding?

    • Enzyme inhibitor
    • Enantiomeric substrate
    • Biological catalyst
    • Allosteric activator

  14. Which interactions hold a drug molecule inside an enzyme active site?

    • Intermolecular forces
    • Covalent bonds
    • Peptide bonds
    • Metallic bonds

  15. What happens to an enzyme molecule at the end of a reaction?

    • It is consumed
    • It remains unchanged
    • It breaks down
    • It becomes saturated

  16. Besides shape, which property of an active site determines substrate specificity?

    • Molecular mass
    • Empirical formula
    • Charge distribution
    • Isotopic ratio

  17. What does a stereospecific active site selectively bind?

    • Non-polar molecules
    • One enantiomer
    • Any structural isomer
    • All optical isomers

  18. Why is computer software used during enzyme inhibitor drug design?

    • To measure pH
    • To predict fit
    • To synthesise enantiomers
    • To purify proteins

  19. Which interactions in an active site are disrupted by extreme pH?

    • Disulfide bridges only
    • Covalent and peptide
    • Metallic and ionic
    • Ionic and hydrogen

  20. How does a competitive inhibitor drug stop enzyme activity?

    • Denatures tertiary structure
    • Breaks covalent bonds
    • Alters substrate shape
    • Blocks active site

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