Lesson Plan

• Describe how temperature influences enzyme activity and identify the optimum temperature.
• Explain how pH affects enzyme structure and activity and identify the optimum pH.
• Conduct a practical investigation measuring enzyme activity under varying temperature and pH conditions.
• Analyse experimental data to construct activity‑temperature and activity‑pH graphs.
• Evaluate the impact of denaturation on catalytic efficiency.

• Potato or liver tissue (source of catalase)
• Hydrogen peroxide solution (substrate)
• Test tubes and rack
• Water baths or hot plates set at 0°C, 20°C, 37°C, 50°C, 70°C
• pH buffer solutions (pH 2, 4, 6, 7, 8, 10)
• Thermometers, pipettes, graduated cylinders
• Stopwatch, safety goggles, lab worksheets
• Projector and computer for diagrams/graphs

Start with a short video showing enzymes speeding up reactions in the body. Ask students what factors they think might affect enzyme function, linking to prior knowledge of active sites. Explain that today they will investigate how temperature and pH change enzyme activity and that they will be able to predict and explain the optimum conditions by the end of the lesson.

1. Do‑now (5'): Quick quiz on basic enzyme concepts.
2. Mini‑lecture (10'): Review active site, optimum conditions, and denaturation.
3. Demonstration (5'): Show a bell‑shaped activity‑temperature curve on the projector.
4. Practical investigation (30'): Groups set up temperature series, add enzyme extract, measure O₂ volume.
5. Data analysis (10'): Calculate reaction rates, plot temperature and pH graphs.
6. Whole‑class discussion (10'): Answer guiding questions about why activity changes.
7. Exit ticket (5'): Write the optimum temperature and pH for catalase and one reason activity drops outside these ranges.

Recap that enzymes work best at specific temperature and pH ranges and that deviations cause denaturation and reduced rates. Students complete the exit ticket summarising the optimum conditions for catalase. For homework, assign a brief report designing an experiment to test the effect of pH on another enzyme (e.g., amylase).