Biology 9700/02 Oct Nov 2006 | Cambridge AS Level Past Papers With Mark Scheme

1. Ecological interactions in mangrove swamps: roles of mangrove trees, hermit crabs, and bacteria in nutrient cycling and energy flow.

2. Rhizobium function in legumes: nitrogen fixation, leghaemoglobin's role in creating anaerobic conditions, and structural similarities with mammalian hemoglobin genes.

3. Chronic bronchitis in smokers: bronchial epithelium damage, increased infection risk, and COPD correlations with cigarette consumption analyzed statistically.

4. Mitotic events in Allium cepa root tips: chromosome movement, mitotic index variation, and genetic consistency maintained through the cell cycle.

5. Immune response and acclimatization: high-altitude red blood cell increase, phagocyte activity against bacteria, and T-helper lymphocyte roles in immune regulation.

6. Cardiac cycle stages: vessel flow patterns, pressure differences in atria and ventricles, and valve functions maintaining unidirectional blood flow.