Biology 9700/53 May June 2023 | Cambridge AS Level Past Papers With Mark Scheme

1. Investigation of photosynthetic rates in Chlorella vulgaris using hydrogencarbonate indicator color changes to measure CO₂ uptake under varying light intensities.

2. Use of Secchi stick and counting chamber to determine C. vulgaris cell density, emphasizing precision in methods for population growth monitoring.

3. Analysis of the effect of grazing by red deer on lichen abundance in mixed woodlands, comparing exclosures to grazed areas using grid-based sampling.

4. Application of statistical methods, including t-tests, to assess the significance of differences in lichen coverage between study sites and sampling heights.

5. Recommendations for experimental standardization, addressing variables such as grid placement, sampling timing, and height on tree trunks.

6. Evaluation of environmental variables on photosynthetic organisms, integrating field sampling techniques and controlled laboratory methodologies.