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LearnCambridge97002025–2027Paper 4 · A Level Structured QuestionsClassification, biodiversity and conservation

Paper 4 · Module

Classification, biodiversity and conservation

2 subtopics≈ 90 min in total

Start the module: Classification and biodiversity Open graphing calculator

Classification and biodiversity
Organisms are classified into three domains (Bacteria, Archaea, Eukarya) and a hierarchy: domain, kingdom, phylum, class, order, family, genus, species; named binomially (Homo sapiens). Eukarya kingdoms: protoctists, fungi, plants, animals. Biodiversity includes ecosystem, species (richness and evenness) and genetic diversity. Measure with random sampling (quadrats at random coordinates) or systematic sampling (transects across a gradient). Mobile animals: mark–release–recapture, $N=\frac{n_1\times n_2}{m_2}$ . Simpson's index $D=1-\sum\left(\frac nN\right)^2$ (0 to 1; higher = more diverse). Spearman's rank tests correlation between two variables: $r_s=1-\frac{6\sum d^2}{n(n^2-1)}$ .
≈ 50 min
Conservation and human impact
Biodiversity is worth conserving for ethical, economic (medicines, food, tourism), ecological (stable ecosystems) and aesthetic reasons. Threats: habitat loss, climate change, pollution, invasive species, overexploitation. In situ conservation protects species in their habitat (national parks, marine reserves, controlling invasive species, managing succession by grazing or coppicing). Ex situ: zoos (captive breeding, genetic diversity using studbooks), botanic gardens, seed banks (dried, frozen seeds), frozen zoos (sperm, eggs, embryos), assisted reproduction (IVF, embryo transfer). CITES controls international trade in endangered species; the Convention on Biological Diversity promotes sustainable use. Reintroduction needs suitable habitat and genetic variety.
≈ 40 min