Biology 9700/02 May June 2004 | Cambridge AS Level Past Papers With Mark Scheme

1. Cardiac conduction system: roles of SAN, AVN, and Purkyne tissue in heartbeat regulation; thicker walls in ventricles for high-pressure blood ejection; effects of atherosclerosis on coronary artery blood flow and heart health.

2. Desert ecosystems: adaptations of plants and animals to arid conditions, trophic levels, and terms like population, community, and ecosystem. Leaf structures for water conservation in low-rainfall areas.

3. Water properties: high specific heat capacity, cohesion, and solvent properties enabling transport in organisms and environmental stability. Potometer experiments showing effects of temperature and wind speed on transpiration rates.

4. Mesophyll cell and red blood cell comparisons: magnification calculation, chlorophyll localization in chloroplasts, and structural differences like lack of organelles in red blood cells.

5. DNA structure: nucleotide components, phosphodiester bonds, and structural differences between DNA and polypeptides. Red blood cell count adaptation at high altitudes for increased oxygen transport.

6. Immune response: T-lymphocyte activation via specific antigens, mitotic cell division for immune cell proliferation, and consequences of dysfunctional T cells in cancer and infection susceptibility.