Biology 9700/31 May June 2007 | Cambridge AS Level Past Papers With Mark Scheme

1. Investigation of lead nitrate's effect on amylase activity using serial dilutions and iodine starch testing, with data recording and results interpretation.
2. Control of pH and identification of sources of error in enzyme activity experiments, including variability in timing and concentration measurements.
3. Use of colorimeters for accurate enzyme activity quantification, highlighting the relationship between lead nitrate concentration and enzymatic inhibition.
4. Evaluation of the hypothesis that lead nitrate inhibits amylase activity at all concentrations, using plotted data for trend analysis.
5. Recommendations for experimental improvements, such as replicates for reliability, precise timing, and consistent preparation of solutions.
6. Plan diagram of a leaf cross-section to study tissue distribution, with magnification calculations and error estimation in thickness measurements.
7. High-power drawing and labeling of guard cells, comparing upper and lower epidermal cells, and analyzing stomatal distribution across leaf surfaces.
8. Structural adaptations of leaves for reduced transpiration, including observations from photomicrographs and comparisons of stomatal placement.