Biology 9700/05 May June 2003 | Cambridge AS Level Past Papers With Mark Scheme

1. Urea content comparison: urease reaction time in renal artery plasma, renal vein plasma, and urine inferred by ammonia release detected via litmus paper color change.

2. Modifications for accuracy: use of precise timing devices, increased urease concentration consistency, and standardization of sample volumes.

3. Tracheal histology: labeled high-power drawings of epithelial and cartilage cells; visible differences include cell shape, nucleus size, and structural arrangement.

4. Transpiration experiment: setup of potometer apparatus, ensuring airtight conditions, and adjusting wind speed with a fan while maintaining temperature, humidity, and light intensity.

5. Volume calculation: measuring water movement in the capillary tube over time, correlating distance traveled with cross-sectional area to determine water absorption rate.