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AS & A Level · AS/A Level

Biology

Enzymes and biomolecules

Name: ____________________Date: October 10, 2026
  1. 1.

    Explain how peptide bonds form and identify the small molecule released.

    [3 marks] · no calculator
  2. 2.

    Explain why a severe change in pH can reduce an enzyme's activity without breaking all peptide bonds.

    [3 marks] · no calculator
  3. 3.

    An enzyme produces 18 micromol of product in the first 30 s. Calculate its mean rate in micromol min^-1 and explain why later measurements may underestimate initial rate.

    [3 marks]
  4. 4.

    Compare competitive inhibition with pure noncompetitive inhibition in terms of substrate binding, Km, Vmax and the effect of very high substrate concentration.

    [5 marks] · no calculator
  5. 5.

    A substitution replaces a charged amino acid with a nonpolar one far from an enzyme's active site. Explain how this could still affect activity and why the sequence change alone cannot predict the exact effect.

    [4 marks] · no calculator
  6. 6.

    Design an investigation to demonstrate reversible slowing of catalase at low temperature and distinguish it from persistent activity loss after high-temperature exposure. Include both treatment-temperature and common-temperature assays using matched aliquots.

    [5 marks] · no calculator

Original, unofficial practice questions from SubjectScout — not official past-paper questions.

Marking points are indicative, not an official mark scheme. Accept equivalent valid methods and supported interpretations that address the task; award each mark once without requiring the model wording.