Biology 9700/42 May June 2010 | Cambridge AS Level Past Papers With Mark Scheme

1. Conservation of the American crocodile in Florida wetlands: nesting site trends, salinity impact on habitat distribution, and reasons for population recovery.

2. Hormonal regulation of ovarian cycles: FSH and LH receptor specificity, steroid synthesis stimulation, and cellular responses to FSH binding.

3. Antibiotic sensitivity in bacteria: zone of inhibition analysis, structural differences between Gram-negative and Gram-positive bacteria, and mechanisms of synthetic penicillin action.

4. Alpha amylase activity in sorghum and rice under temperature variations: enzyme tertiary structure differences affecting function and cereal crop adaptation in diverse climates.

5. Speciation in Drosophila: DNA sequence divergence, geographic isolation influence, and evidence of allopatric speciation.

6. Cleft iris inheritance: sex-linked recessive allele transmission, genetic diagram construction, and offspring phenotype predictions.

7. Krebs cycle processes: decarboxylation, dehydrogenation, reduced NAD role in anaerobic yeast respiration, and differences between lactate and ethanol fermentation pathways.

8. Gene technology applications: fluorescent marker genes for identifying transformations, and advantages and challenges of genetically modified crops with enhanced vitamin A.