d) Carrying capacity
20. Why are aggregates important in determining the quality of the soil as a habitat for organisms
21. What is soil quality
22. How would you define a "healthy" agricultural soil
23. How can biological diversity and crop rotation benefit soil quality
24. Describe the biogeochemical cycles of carbon.
25. Describe the role of earthworms in soils.
26. Describe the biogeochemical cycles of nitrogen.
27. What are the impacts of agricultural activities and practices (e.g. fertilizers, pesticides, physical disturbance) on soil biodiversity and the capacity of the soil to undertake its functions
28. Describe the relationship between land management and greenhouse effect
29. What are the ecological consequences for nitrification in soils
30. How can organic farming increase farmer wealth andbiological diversity
31. What is the risk of gene flow from GM (genetic modified) plants to microbes
32. Describe the roles of soil biodiversity in ecosystem function, resilience and recovery

33. Describe the interactions between soil organisms.
34. Describe the differences between r-strategy and K-strategy organisms.
35. What are the roles of phosphorus and nitrate in the eutrophication of rivers and lakes
36. List the chemicals that will cause ozone destruction, and deduce the mechanism for at least one of the chemicals, which you give, leading to O3 disappearance.
37. Photochemical smog has become one of air pollution problems in many urban areas in the world. Demonstrate the reactions causing photochemical smog and propose the methods to reduce it.
38. In December 1997, world leaders met in Kyoto, Japan, to develop a strategy for controlling carbon dioxide and other greenhouse gas emissions on a global scale. As part of the agreement, an overall goal of reducing greenhouse gases by at least 5% below 1990 levels by 2010-2012 was set. However, the objective of the Kyoto Protocol may be defeated if "some events" occur. What are the events

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