- Explain why gross productivity decreased as the woodland matured (2 marks)
- Suggest 2 ways in which crop rotation may lead to high crop yields (2 marks)
- Leguminous crop plants have nitrogen-fixing bacteria in nodules on their roots. On soils with a low concentration of nitrate ions, leguminous crops often grow better than other types of crops. Explain why. (2 marks)
- Very high concentrations of fertiliser to soil can reduce plant growth. Use your knowledge of water potential to explain why (2 marks)
- Explain why an increase in shoot biomass can be taken as a measurement
of net primary productivity (2 marks)
- Explain why CO2 uptake is a measure of net productivity (1 mark)
- Use information from the graph to find the gross rate of photosynthesis at 20°C and
medium light intensity!!!!! (1 mark) - 2011