The principles and importance of taxonomy. Classification systems consist of a hierarchy in which groups are contained within larger composite groups and there is no overlap. The phylogenetic groups are based on patterns of evolutionary history. A species may be defined in terms of observable similarities and the ability to produce fertile offspring. One hierarchy comprises Kingdom, Phylum, Class, Order, Family, Genus, Species. Candidates should be able to appreciate the difficulties of defining species and the tentative nature of classifying organisms as distinct species.

Taxonomy is the system used to group organisms, it is important to scientist to establish the relationships between different species.

All organisms originated from the same organism but through evolution have ended up with significant amounts of variation.

Phylogenetic groups are how recently two species have been related (how recently they evolved apart into different species).

Sometimes organisms are organised due to observable physical characteristics which do not necessarily mean they are closely genetically related.

Classification is not yet perfected due to the sheer number and the complexity of life on earth.

The most common system is:

scunderwood

The definition of a species is a group of organisms which can breed to create fertile offspring.

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