Biology 9700/21 May June 2011 | Cambridge AS Level Past Papers With Mark Scheme

1. Structural features of the ciliated epithelium in the trachea: protection via mucus secretion and ciliary action, with mitotic cell division processes.

2. Carbon dioxide transport: diffusion into red blood cells, reaction with water catalyzed by carbonic anhydrase, and its effect on oxygen dissociation from hemoglobin.

3. Differences between mRNA and DNA: nucleotide composition, sugar type, and single-strand vs. double-strand structure; role of mRNA in protein synthesis in cytoplasm.

4. Enzyme kinetics: sucrase activity with varying sucrose concentrations, reaction conditions for hydrolysis, and factors affecting enzyme performance.

5. Biological molecule identification: peptide bonds, energy storage polymers, structural helical formations, and hydrophobic components of membranes.

6. Measles vaccination: active vs. passive immunity, immunization timing considerations, and WHO recommendations for achieving 90% vaccination coverage to reduce child mortality rates.