Biology 9700/42 Oct Nov 2020 | Cambridge AS Level Past Papers With Mark Scheme

- Photosynthesis mechanisms in C3 and C4 plants, including adaptations to temperature and atmospheric conditions.
- Genetic variation in goat breeds, impact of environmental factors on milk yield, and selective breeding strategies for high yield in local conditions.
- Evolutionary processes leading to subspecies differentiation in Mus musculus, including hybridization and reproductive isolation mechanisms.
- Genetic basis of sickle cell anemia, inheritance patterns, and implications of genetic screening and natural selection in malaria-endemic regions.
- Tyrosinase gene mutations affecting pigmentation in mammals, including silent mutations and premature stop codons in albino cats.
- Mechanisms of opioid action on pain perception, spinal reflex features, and roles of sensory and motor neurons in reflex arcs.