Biology 9700/51 May June 2013 | Cambridge AS Level Past Papers With Mark Scheme

1. Gibberellin effect on maize germination tested by measuring amylase activity via starch hydrolysis, using iodine-stained agar plates for brown area analysis.

2. Method standardization: gibberellin concentration, incubation time, agar setup, and iodine test to assess hypothesis linking gibberellin to increased amylase activity.

3. Limitations of amylase activity estimation by visual area analysis, including subjective measurement, starch distribution variability, and iodine staining inconsistency.

4. Trends in aerobic and anaerobic bacteria in stored soil layers, influence of oxygen availability, and dehydrogenase enzyme activity as a metabolic indicator.

5. Error bar interpretation for data reliability, t-test for significance in dehydrogenase activity differences, and prediction of bacterial count using enzyme activity data.