A branch of biology that identifies, names, and classifies species based on their natural relationships.

The categorizing of organisms.

The taxonomic group of one or more kingdoms. It is the highest level of the hierarchy.

An organism whose cells do not contain a nucleus.

An organism whose cells do contain a nucleus.

A taxonomic group of related phyla or divisions.

An organism that cannot make its food, but must consume it.

An organism capable of making its own food.

A taxonomic group of related classes.

A taxonomic group that contains one or more related orders.

A taxonomic group that contains related families.

A taxonomic group of similar, related genera.

A taxonomic group of similar species.

A taxonomic group of organisms that have similar traits and are able to produce fertile offspring.

A naming system that gives each organism a two-word scientific name (genus + species name).

A series of descriptions arranged in pairs that leads the user to the identification of an unknown organism - unknown to the searcher, but not unknown to scientists.

A branched diagram that shows the relationships among organisms, including a common ancestor.

A family tree shows the relationships among family members, including common ancestors.

An organism that lives under extreme environmental conditions.

Prokaryotes whose cell walls do not contain peptidoglycan and live in extreme environments.

A single-celled, prokaryotic microorganism that lives in normal environments.

A mostly unicellular (although can be multicellular or colonial) eukaryote whose cell walls may contain cellulose, can be plantlike, animal-like, or funguslike.

Protists that resemble a tiny animal.

An eukaryotic, multicellular (sometimes unicellular) organism that absorbs nutrients from organic material in its environment.

Long, threadlike structures that make up the body of fungi and form an underground structure that absorbs minerals and water.

An underground network of hyphae.