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: 

4.1 understand the terms population, community, habitat and ecosystem 

4.2 practical: investigate the population size of an organism in two different areas using quadrats 

4.3B understand the term biodiversity 

4.4B practical: investigate the distribution of organisms in their habitats and measure biodiversity using quadrats 

4.5 understand how abiotic and biotic factors affect the population size and distribution of organisms