State one physical factor and one human factor not shown on the diagram that contribute to a loss of biodiversity.

Explain how any one of the factors given on the diagram contributes to a loss of biodiversity in tropical rainforests.

Explain three reasons why biodiversity in tropical rainforests should be preserved.

Award 1 mark for each factor.

Possible physical factors include: natural hazards such as floods, disease, droughts, volcanic eruptions, fires.

Possible human factors include: deforestation, mining, expansion of agricultural areas, expansion of settlements, overexploitation of susceptible species leading to their extinction.

The explanation will depend on the factor chosen, but should provide details of precisely how the factor can contribute to a loss of biodiversity, as opposed to simply causing or leading to deforestation. Award up to 2 marks for explanations of the factor, for example, causes of deforestation, reserving the final 2 marks for comments which show a clear understanding of how this reduces biodiversity.

No credit may be given for explanations of a second factor, or for explanation of any factor not shown on the diagram.

Award 1 mark for each basic explanation, with additional 1 mark for extension and or exemplification.

The reason for preservation must be linked to biodiversity.

Possible reasons include: the economic value of plant and animal species found therein; the importance of biodiversity in maintaining a healthy forest structure, with its implications for watershed protection; the importance of a healthy ground cover for soil protection; enhancing the value of rainforests for ecotourism; conserving global genetic diversity; concepts of stewardship/environmental ethics.

Human factor – deforestation – was very common. Candidates struggled more with identifying a physical factor, with some choosing another human-induced factor.

On the whole well answered if "cattle ranching" or "introduction of alien species" was chosen with answers directly linked to biodiversity loss. Answers that referred to climate change or pollution tended to be very vague and not specific to loss of biodiversity in tropical rainforests. Unfortunately some candidates did not use a factor "given on the diagram" and as such could not score any marks for this question.

The best candidates were able to explain three reasons why biodiversity in tropical rainforests should be preserved. However, there were instances where candidates repeated similar points in the sub-parts of the question and could not be awarded further credit. Often the importance of biodiversity was not addressed and the answers lacked extension and development. It was also common for weaker candidates to concentrate on explanations for preserving tropical rainforests rather than the specific preservation of biodiversity within it.