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C1.1.10—Effect of enzymes on activation energy

Enzymes lower activation energy by providing an alternative pathway while leaving reactant and product energy levels unchanged overall during catalysis.

Syllabus
First assessment 2025
Objective
C1.1.10
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper1
Typical marks1

Common command terms

  • Predict
  • Identify

Recent exam appearances

May 2023Paper2 ["HL"] · TZ22(c)[ 1 ]C1.1.10—Effect of enzymes on activation energy
May 2018Paper2 ["HL"] · TZ15(d)[ 1 ]C1.1.10—Effect of enzymes on activation energy
May 2015Paper1 ["HL"] · TZ211[ 1 ]C1.1.10—Effect of enzymes on activation energy
November 2012Paper1 ["HL"] · TZ025[ 1 ]C1.1.10—Effect of enzymes on activation energy
May 2012Paper1 ["HL"] · TZ127[ 1 ]C1.1.10—Effect of enzymes on activation energy
Practice this objective

Coverage 2012–2023 · Updated 15 Jul 2026

Concept essentials

  • Enzymes lower the activation energy required for reaction.
  • Catalysed and uncatalysed reactions have the same reactant and product energy levels.
  • Energy-profile graphs show a lower peak for the enzyme-catalysed pathway.
  • Lower activation energy increases reaction rate.
ConceptIB Biology HL