Biology 9700/22 May June 2012 | Cambridge AS Level Past Papers With Mark Scheme

1. Transport mechanisms in cell membranes: active transport of sodium ions, passive diffusion of oxygen, osmosis for water, exocytosis of mucin, and facilitated diffusion of glucose.

2. Plasma cell structural functions: rough endoplasmic reticulum for protein synthesis, Golgi apparatus for protein modification, and vesicles for antibody secretion.

3. Differences between evaporation and transpiration in leaves; stomatal density effects on transpiration rate, influenced by weather conditions like temperature and humidity.

4. Glutathione from sour cherries repairing DNA damage; peaches reducing bronchial inflammation in smokers, highlighting fruit’s protective health effects.

5. DNA and RNA distinctions in nucleotide structure, tRNA’s role in polypeptide synthesis, and peptide bond formation via condensation.

6. Cholera statistics by region; fatality rate calculations, inhibitors targeting NQR enzyme as a therapeutic strategy, and socioeconomic factors affecting disease spread.

7. Nitrogen cycle roles of bacteria: nitrification by Nitrosomonas, denitrification by Bacillus, nitrogen fixation by Azospirillum, and organic matter breakdown by Streptomyces.

8. Increased phosphate uptake promoting plant growth via enhanced ATP production and nucleotide synthesis, improving metabolic efficiency and biomass accumulation.