The following sub-topics are covered in this section. 

(a) The organism in the environment 

(b) Feeding relationships 

(c) Cycles within ecosystems 

(d) Human influences on the environment

Students should:

4.12 understand the biological consequences of pollution of air by sulfur dioxide and carbon monoxide 

4.13 understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases 

4.14 understand how human activities contribute to greenhouse gases 

4.15 understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and its consequences 

4.16 understand the biological consequences of pollution of water by sewage 

4.17 understand the biological consequences of eutrophication caused by leached minerals from fertiliser 

4.18B understand the effects of deforestation, including leaching, soil erosion, disturbance of evapotranspiration and the carbon cycle, and the balance of atmospheric gases