Classification of Living Things Introduction to the Modern System

Need for Classification Living things have characteristics in common such as the functions or activities that are necessary to maintain life. In order to study living things in an organized and efficient way, biologists find it necessary to classify or group organisms in a logical way.

Basis for Classification The most common basis for classifying organisms is similarities in structure. Such as the exoskeleton, appendages, organs, or cellular structures (chloroplasts, nuclei). Biochemical and genetic similarities, in patterns of embryological development, and fossil evidence are also used for classification.

Modern System of Classification Our modern classification system assumes that present day forms of life developed from earlier forms. The Kingdom is the largest classification group. Today, most biologists group organisms into a six-kingdom system: Archaebacteria (ancient bacteria), Eubacteria (true bacteria), Protista, Fungi, Plantae, and Animalia

Classification Standards The six kingdom system is based on the following standards: 1. The presence or absence of a nuclear membrane within the cell. 2. Whether the organism is unicellular (one-celled) or multicellular (many celled) 3. Type of nutrition

Subdivisions of Kingdoms Phylum Class Order Family Genus Species -includes all organisms of the same kind

Scientific Names Common names are not used, Latin is used for scientific naming because it is the universal language of science and it is accepted worldwide. Binomial Nomenclature- consist of a genus and species name for each organism. These names are written in italics. The genus name is capitalized and the species name is not capitalized. Homo sapiens………….man Canis familaris…………dog