Biology 9700/53 Oct Nov 2012 | Cambridge AS Level Past Papers With Mark Scheme

1. Investigation of nitrate concentration effects on Chlorella growth using sodium nitrate in varying concentrations, with population growth monitored via haemocytometer.

2. Preparation of sodium nitrate solutions through serial dilution, controlled variables like sunlight exposure and room temperature, and control setup using nitrate-free medium.

3. Calculation of mean percentage cell increase to normalize growth data, highlighting nitrate concentration's impact on Chlorella cell proliferation.

4. Modification suggestions to find optimal nitrate concentration; inclusion of phosphate effects on Chlorella growth in polluted environments.

5. CAPD dialysis effectiveness test using urea concentration strips; iron supplementation effects on hemoglobin, iron, and ferritin levels in anemic dialysis patients.

6. Statistical reliability of hemoglobin and iron level changes through SM and t-tests; evidence favoring injection over oral iron supplementation despite study limitations.