H2 Biology Practical: Enzyme Kinetics (Catalase) Guide

Q: What does H2 Biology Practical: Enzyme Kinetics (Catalase) Guide cover?
A: Run a syllabus-aligned catalase assay with serial dilutions, temperature control, initial rate estimation, and spreadsheet-backed graphs so MMO/PDO/ACE marks are predictable.

TL;DR
Treat enzyme practicals as controlled investigations: set a single independent variable, keep conditions constant, record volumes/times consistently, and calculate initial rate from the linear region. Use a clean serial dilution, control temperature, and graph rate vs substrate concentration with error bars for ACE credit.

Status: SEAB H2 Biology (9477, first exam 2026) syllabus and Scheme of Assessment last checked 2025-11-29 (PDF last modified 2025-11-28). Paper 4 remains 2 h 30 min, 50 marks, with Planning at 4 % and MMO/PDO/ACE at 16 % combined; enzyme rate investigations stay within Core Idea 3’s practical expectations.

1 Aim & overview (catalase + hydrogen peroxide)

• Investigate how substrate concentration affects catalase activity using the oxygen evolved.
• Keep pH and temperature constant; measure initial rate via gas volume/time or pressure change.
• Recommended timing: 60 minutes end-to-end with one variable across 5-6 levels.
• Syllabus alignment: SEAB H2 Biology (9477, first exam 2026) expects investigation of enzyme-catalysed rates via gas output from catalase across substrate concentrations; Paper 4 carries 20% of H2 with Planning at 4% and MMO/PDO/ACE at 16% combined.

2 Apparatus & reagents

• Catalase source: yeast suspension or blended potato (filtered).
• Substrate: hydrogen peroxide standards (e.g., $0.2\%$, $0.4\%$, $0.6\%$