Lesson 3.1.4.2.2

3.1.4.2.2 Factors affecting enzyme-controlled reactions Quiz: AQA Biology, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.4.2.2, Factors affecting enzyme-controlled reactions: 20 multiple choice questions for the AQA Biology (7402), Unit 1: Biological molecules, written with Revision Ninja.

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The 20 questions

  1. Where does a competitive inhibitor bind to an enzyme?

    • Allosteric site
    • Substrate site
    • Peptide backbone
    • Active site

  2. Where does a non-competitive inhibitor bind to an enzyme?

    • Active site
    • Reactive site
    • Allosteric site
    • Substrate site

  3. How does increasing substrate concentration affect a reaction with a competitive inhibitor?

    • Reduces inhibition
    • Increases inhibition
    • Denatures the enzyme
    • Has no effect

  4. Why does the reaction rate plateau at high substrate concentrations with fixed enzyme concentration?

    • Enzymes denatured
    • Active sites saturated
    • Inhibitors bound
    • Substrate exhausted

  5. Why does the reaction rate fall rapidly above an enzyme's optimum temperature?

    • Enzyme concentration drops
    • Enzyme denatures
    • Activation energy rises
    • Substrate breaks down

  6. How does a change in pH affect the structure of an enzyme's active site?

    • Denatures substrate molecules
    • Alters R-group ionisation
    • Hydrolyses polypeptide chain
    • Breaks peptide bonds

  7. Which factor limits the reaction rate when substrate concentration is very high?

    • Enzyme concentration
    • Activation energy
    • Substrate concentration
    • Competitive inhibitor

  8. Why does reaction rate increase as temperature rises towards the optimum?

    • Less enzyme denaturation
    • More active sites
    • More kinetic energy
    • Lower activation energy

  9. Why can increasing substrate concentration not overcome non-competitive inhibition?

    • Active site altered
    • Inhibitor is consumed
    • Substrate is blocked
    • Enzyme is broken

  10. In an iodine clock experiment, a colour change takes 40 s. What is the rate of reaction in s^-1?

    • 2.5 s^-1
    • 40 s^-1
    • 0.4 s^-1
    • 0.025 s^-1

  11. An enzyme with optimum pH 7 shows lower activity at pH 5. What caused this?

    • Activation energy doubled
    • Substrate fully consumed
    • Enzyme destroyed completely
    • Active site altered

  12. What happens to reaction rate when competitive inhibitor concentration is doubled with constant substrate?

    • It stays constant
    • It decreases
    • It doubles
    • It increases

  13. A student measures the rate of an enzyme-controlled reaction at 30 C and at 40 C. The rate doubles between these temperatures. What is the Q10 value for this range?

    • 1
    • 2
    • 10
    • 4

  14. Which change increases the maximum rate (Vmax) of an enzyme-catalysed reaction?

    • Increase substrate concentration
    • Decrease reaction temperature
    • Add competitive inhibitor
    • Increase enzyme concentration

  15. Why does doubling substrate concentration not always double the rate of reaction?

    • Activation energy rises
    • Substrate denatures
    • Active sites saturate
    • Enzymes are consumed

  16. Which type of enzyme inhibition can be overcome by increasing substrate concentration?

    • Irreversible inhibition
    • End-product inhibition
    • Competitive inhibition
    • Non-competitive inhibition

  17. Which bonds in an enzyme's tertiary structure are disrupted by changes in pH?

    • Glycosidic and ester
    • Disulphide and peptide
    • Hydrogen and ionic
    • Peptide and phosphodiester

  18. What type of variable must be kept constant during an enzyme activity investigation?

    • Independent variable
    • Categorical variable
    • Dependent variable
    • Control variable

  19. What term describes the temperature at which an enzyme-catalysed reaction occurs fastest?

    • Critical temperature
    • Optimum temperature
    • Denaturation temperature
    • Maximum temperature

  20. What pH environment is optimal for stomach enzymes such as pepsin?

    • Neutral
    • Basic
    • Acidic
    • Alkaline

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