Biology
Energy transfer and experimental design
- 1.
Primary producers capture 20000 kJ m^-2 year^-1. Herbivores gain 1800 kJ m^-2 year^-1 in biomass. Calculate energy-transfer efficiency and give two reasons why it is below 100%.
[3 marks] · no calculator - 2.
Design an investigation into the effect of light intensity on photosynthesis in an aquatic plant using oxygen volume produced per minute. Explain how you would improve validity and reliability.
[4 marks] · no calculator - 3.
A monohybrid cross predicts a 3:1 phenotype ratio. Observed counts are 72 dominant and 28 recessive. Calculate chi-squared. Using a 5% critical value of 3.84 for one degree of freedom, interpret the result.
[5 marks]
Marking points are indicative, not an official mark scheme. Accept equivalent valid methods and supported interpretations that address the task; award each mark once without requiring the model wording.