Biology 9700/42 May June 2018 | Cambridge AS Level Past Papers With Mark Scheme

1. Conservation challenges for the Sumatran tiger, including habitat destruction, genetic diversity, and the role of coordinated breeding programs in zoos to maintain genetic health.

2. Autosomal linkage in sweet pea plants, demonstrated through dihybrid crosses, genetic linkage effects on phenotypic ratios, and crossover value calculations for gene distance estimation.

3. Meiosis as a source of genetic variation, highlighting prophase I events, independent assortment, and environmental factors influencing traits like body mass in birds.

4. Adaptive evolution of Drosophila species to toxic environments, with isolation effects on speciation and the application of bioinformatics to estimate evolutionary timelines.

5. Gene therapy techniques for stroke treatment using cDNA and adeno-associated viral vectors, evaluating survival rates, brain damage reduction, and behavioral improvements in experimental mice.

6. Photosynthetic efficiency in C4 plants, the role of specialized cell arrangements, and comparative enzyme activity at varying temperatures in C3 versus C4 plants.

7. Neurophysiology of synaptic transmission, including mechanisms of acetylcholine release, effects of local anesthetics, and the functional architecture of neuromuscular junctions.

8. Osmoregulation processes, including selective reabsorption in the kidney and hypothalamic-pituitary roles in water balance.