Biology 9700/03 Oct Nov 2002 | Cambridge AS Level Past Papers With Mark Scheme

1. Biodiversity and Ecosystem Impact:
- Differences in earthworm and cnidarian body plans; worm locomotion via longitudinal and circular muscles with setae.
- Deforestation impacts: increased edge tree mortality and seedling density variations due to fragment size and edge effects.

2. Biotechnology Applications:
- Ethanol production via starch fermentation; biofuel ecological benefits (reduced emissions, renewable energy source).
- Genetic engineering advantages for insulin production over extraction from animals; reduced immune reaction risks and ethical concerns.

3. Growth and Reproduction:
- Relative body proportions during human development; smaller head ratio in adults due to slower growth of cranial structures.
- Birth weight effects: higher mortality at extremes; smoking linked to lower birth weight and fetal developmental issues.

4. Seed Germination and Plant Growth:
- Oil reserves in seeds provide higher energy density compared to starch.
- Gibberellin actions in germination: activating amylase for starch hydrolysis and promoting cell elongation.

5. Applications of Genetics:
- Shell banding inheritance in Cepaea nemoralis involving gene interactions and tight linkage with shell color.
- Electrophoresis detecting deletions in genes like β-thalassemia; gene therapy challenges with recessive and dominant mutations.

6. Selective Breeding and Genetic Mutations:
- Rare breed maintenance to preserve genetic diversity; selective breeding in livestock for desirable traits.
- Mutation comparison: CF caused by recessive CFTR gene mutations, HD from dominant trinucleotide repeats. Rapid bacterial resistance spread due to horizontal gene transfer.