Biology 9700/01 Oct Nov 2002 | Cambridge AS Level Past Papers With Mark Scheme

1. Prokaryotes and Cellular Structures:
- Prokaryotic characteristics include circular DNA and lack of membrane-bound organelles.
- Nucleic acids absent in the Golgi body; mitochondria cristae surface area supports enzyme-driven ATP production.

2. Osmosis and Water Potential:
- Potato cell water potential determined by isotonic sucrose solution concentration; percentage length change graphed against water potential.

3. Biomolecules and Enzyme Function:
- Glycogen hydrolysis involves breaking glycosidic bonds.
- Protein tertiary structure maintains enzyme globular shapes; ionic bonds between amino acids disrupted by pH changes.

4. DNA and Protein Synthesis:
- DNA polymerase synthesizes complementary DNA strands during replication.
- mRNA transcription follows complementary base pairing rules; codons on mRNA match tRNA anticodons during translation.

5. Circulatory and Respiratory Systems:
- Sinoatrial node acts as pacemaker in mammals.
- Nicotine and caffeine increase heart rate; carbon monoxide in tobacco disrupts oxygen transport.

6. Ecosystems and Nutrient Cycles:
- Energy transfer inefficiency in food chains; only 1% of light energy is converted by plants, with 10% passed to next trophic level.
- Denitrifying bacteria reduce nitrates to nitrogen gas; carbon cycle includes CO₂ release during respiration.