Q.Why is classification of living organisms necessary? Give two reasons.

Classification is the process of grouping things into convenient categories based on characters that can be observed and compared. Biologists use this everyday idea deliberately: just as a supermarket organises its shelves into groceries, cosmetics, toys, stationery and snacks so that customers can find things quickly, and a library sorts books alphabetically or by genre, living organisms are grouped so that the enormous diversity of life becomes something a person can actually study. Without such organisation, both everyday shopping and scientific biology would waste enormous amounts of time. The formal scientific category used at each level of this grouping is called a taxon (plural taxa) — for example, Kingdom Animalia is a taxon that includes every multicellular animal, from reptiles to mammals.

The textbook identifies five specific reasons classification is needed: to identify and differentiate closely related species from one another; to understand the variation that exists among species; to understand how species have evolved over time; to construct a phylogenetic tree showing relationships among different groups; and, most practically, to make it possible to study living organisms conveniently at all, given how many of them exist.

Because classification depends on comparing characters, taxonomists rely on external and internal structural features, developmental processes, and ecological information about each organism as the raw material for their work. This combination of characterisation, identification, nomenclature (naming) and classification together forms the basic scientific stages of taxonomy, the subject introduced in the following section.