Biology 9700/51 May June 2021 | Cambridge AS Level Past Papers With Mark Scheme

- Enzyme β-galactosidase, substrate ONPG, product ONP, colorimetric analysis, absorbance measurement.
- Dilution preparation, buffer solution, pH 8, final volume, concentration effects.
- Independent variable: substrate concentration; dependent variable: initial rate of reaction.
- Inhibitor X, competitive inhibition, method for data collection, reaction mixtures.
- Chi-squared test, null hypothesis, observed vs. expected results, phenotype ratios.
- Drug comparison: proton pump inhibitors (PPIs) vs. H2 receptor antagonists (H2 RAs), symptom relief analysis, statistical significance.