Biology 9700/34 Oct Nov 2019 | Cambridge AS Level Past Papers With Mark Scheme

1. Investigation of pH effects on methylene blue release from potato cells, including standardization of surface area, buffer solution volume, and qualitative assessment of color intensity for pH estimation.

2. Effect of soil pH on grass growth measured by mean dry mass of grass; graphical representation of data and analysis of trends in growth performance across varying pH levels.

3. Adaptations of xylem cells identified through structural features, including cell wall thickness and arrangement; drawing and labeling of plant leaf tissues with emphasis on vascular bundle details.

4. Calculation of actual dimensions and magnification of leaf sections using eyepiece graticule calibration and stage micrometer measurements, followed by comparative analysis of observable differences between leaves.

5. Modifications to procedures for more accurate pH determination or for assessing temperature effects on methylene blue release, emphasizing controlled variable adjustments and measurement techniques.

6. Mechanisms of mineral absorption affected by low soil pH, including protein function in root cell membranes and its influence on plant growth in acidic conditions.