Biology 9700/53 Oct Nov 2021 | Cambridge AS Level Past Papers With Mark Scheme

- Independent variable: temperature; dependent variable: volume of carbon dioxide produced.
- Stirring mixture: ensures uniform distribution of yeast and glucose, promotes consistent fermentation.
- Methodology: temperature variation, measure CO2 production, control variables, replicate trials, record data.
- Graph prediction: CO2 production vs. temperature, axes labeled with units, expected maximum rate identified.
- Crabtree effect: comparison of S. cerevisiae and C. tropicalis, evidence of fermentation behavior under high glucose and oxygen conditions.
- Species diversity analysis: correlation between latitude and bird species count, statistical significance, limitations of sampling method.