Dichotomy

In biology, a dichotomy is a distribution of genera into two species. Such dichotomies are used as part of the process of classifying species, to build a taxonomic key. When classifying, a series of questions is asked which narrows down what is being examined, to indicate where it belongs in the hierarchy.

A well known dichotomy is the question "does it have a backbone?", used to divide species into vertebrates and invertebrates.

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