Biology 9700/01 May June 2003 | Cambridge AS Level Past Papers With Mark Scheme

1. Cellular Components:
- Rough endoplasmic reticulum as the first site of increased radioactivity from amino acids.
- Phospholipid bilayer arrangement due to hydrophilic heads facing water and hydrophobic tails inward.

2. Water Potential and Diffusion:
- Osmosis effects in plant tissues in sucrose solutions; isotonic point identified from length ratio graphs.
- Water potential dynamics in plant cells and their environment, with movement influenced by potential gradients.

3. Biomolecules and Enzymes:
- Glycosidic bond formation in polysaccharides by condensation.
- Enzyme non-competitive inhibitors bind non-active sites, unaffected by substrate concentration.

4. Respiration and Circulation:
- Aerobic respiration's efficiency over anaerobic due to higher ATP yield.
- Human hemoglobin dissociation curve insights; pulmonary artery oxygen levels and aerobic exercise limitations.

5. Health and Immunity:
- Tobacco nicotine increasing blood pressure.
- Natural passive immunity from maternal antibodies protecting newborns temporarily.

6. Ecosystems and Niches:
- Nitrogen cycle roles of nitrifying, denitrifying, and nitrogen-fixing bacteria.
- Competitive exclusion principle preventing species from occupying identical ecological niches.