key term - Kingdom

Definition

A kingdom is one of the highest taxonomic ranks used to classify organisms in the biological hierarchy. It groups together all forms of life that share fundamental structural and functional characteristics.

5 Must Know Facts For Your Next Test

1. There are currently six recognized kingdoms: Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria.
2. The classification into kingdoms is based on criteria such as cell type (prokaryotic or eukaryotic), mode of nutrition, and reproductive strategies.
3. Kingdoms are further divided into phyla, classes, orders, families, genera, and species.
4. The concept of kingdoms has evolved over time; initially there were only two (Plantae and Animalia) before expanding to include microorganisms.
5. Carl Linnaeus originally proposed a two-kingdom classification system in the 18th century which has since been expanded to better reflect evolutionary relationships.

Review Questions

Related terms

Phylum:

A taxonomic rank below kingdom and above class that groups organisms based on major body plans or organizational patterns.

Species:

The most specific level of organism classification which includes individuals that can interbreed and produce fertile offspring.

Taxonomy:

The science of classifying organisms to construct internationally shared classification systems with each organism placed into increasingly more specific categories.