Biology 9700/21 May June 2012 | Cambridge AS Level Past Papers With Mark Scheme

1. Blood vessels, immune cells, and epithelial tissues identified in the context of respiratory and circulatory systems, including tracheal support structures.

2. Comparison of cellular organelles' visibility under light and electron microscopy, roles of vacuoles in plant cells, and the importance of plasmodesmata in transport.

3. Haemoglobin's oxygen-binding affinity in sickle cell anemia, with oxygen dissociation curve analysis, high-altitude adaptation mechanisms, and limits of vaccination for genetic disorders.

4. Enzymatic activity of penicillinase in antibiotic resistance, structural features influencing substrate binding, and strategies to reduce bacterial resistance through antibiotic use.

5. Life cycle analysis of Dictyostelium discoideum, reduction division importance in meiosis, ammonium ion excretion, and transporter proteins' roles in nutrient cycling.

6. DNA base pairing supported by Chargaff’s rules, structural significance of hydrogen bonds, and differences in viral and organismal DNA base ratios linked to genomic organization.