Biology 9700/51 Oct Nov 2023 | Cambridge AS Level Past Papers With Mark Scheme

1. Investigation of ascorbic acid concentration changes in apples during ripening, using DCPIP titration to measure reduction levels.

2. Practical method involving dilution of DCPIP stock solutions, preparation of apple extracts, and quantitative assessment of ascorbic acid via color change.

3. Analysis of Pearson’s linear correlation as a statistical tool to evaluate the relationship between ripeness and ascorbic acid concentration.

4. Comparative study of β-carotene levels in ripe apples and other fruits, supporting nutritional evaluations of vitamin A sources.

5. Experiment on enzyme activity, comparing trypsin from Atlantic salmon and domestic pigs at 20°C, measuring gelatin breakdown rates.

6. Application of statistical tools like t-tests to determine significance in enzyme activity differences, with discussions on ectothermic vs. endothermic adaptations.