State what $N$ and $n$ stand for in this formula.

$N$:

$n$:

Discuss three reasons for the conservation of biodiversity in rainforests.

$\left. {\begin{array}{*{20}{l}} {N:}&{{\text{total number of organisms of all species found/in population;}}} \\ {n:}&{{\text{number of organisms of a particular species;}}} \end{array}} \right\}$ (both needed)

ethical: life should be respected / cultural importance for (local human indigenous) population / (human indigenous) population’s ability to live sustainably within ecosystem might be affected / richness for future generations;

ecological: native species might be replaced by alien species / extinction of one species can lead to the extinction of many others / interdependency of species may be disrupted/negative effects on food chains /soil erosion/floods occur with deforestation / rainforests act as a carbon sink which helps reduce global warming;

economic: medicines or materials not found yet / genes of wild species need to be preserved / ecotourism improves local economy/encourages local conservation / plant sources of pharmaceuticals lost if species extinct / crops may be improved with alleles from wild plants;

aesthetic: loss of beauty of wild / inspiration for artists;

(Words in italics alone are not worth marks)

Candidates had a difficult time stating precisely what N and n stand for in the Simpson Diversity Index.

This question on reasons for conserving rainforests has been answered frequently and candidates were often able to get the full 3 marks for giving a reason that was ethical, ecological, economic or aesthetic in nature.