Summary 3.4.6 Biodiversity within a community and 3.4.7 Investigating diversity

Biodiversity can relate to a range of habitats, from a small local habitat to the Earth. Species richness is a measure of the number of different species in a community. An index of diversity describes the relationship between the number of species in a community and the number of individuals in each species. Calculation of an index of diversity ( d ) from the formula d = N ( N - 1 ) Σ n ( n - 1 ) where N = total number of organisms of all species and n = total number of organisms of each species. Farming techniques reduce biodiversity. The balance between conservation and farming. Genetic diversity within, or between species, can be made by comparing: the frequency of measurable or observable characteristics the base sequence of DNA the base sequence of mRNA the amino acid sequence of the proteins encoded by DNA and mRNA. Students should be able to: interpret data relating to similarities and differences in the base sequences of DNA and in the amino acid sequences of proteins to suggest relationships between different organisms within a species and between species appreciate that gene technology has caused a change in the methods of investigating genetic diversity; inferring DNA differences from measurable or observable characteristics has been replaced by direct investigation of DNA sequences. Knowledge of gene technologies will not be tested. Quantitative investigations of variation within a species involve: collecting data from random samples calculating a mean value of the collected data and the standard deviation of that mean interpreting mean values and their standard deviations. Students will not be required to calculate standard deviations in written papers.