LG 5 Classification

Scientific NamesTwo-Word System –Binomial Nomenclature –

Linnaeus’s System of ClassificationCarolus Linnaeus –Hierarchy of Classification –

Kingdoms and Domains2 Kingdoms –5 Kingdoms –6 Kingdoms –

The Three-Domain SystemEukarya –Bacteria –Archaea –

Characteristics Used to Group Organisms into KingdomsCell Type –Cell Structures –Number of Cells –Mode of Nutrition –

Identifying Organisms Dichotomous Keys –

Unit VEvolution

LG 5Explain how species are classified

using the science of taxonomy.

Scientific Names• Each species is

assigned a two-word scientific name that is the same throughout the world, even though common names may be different.

• This eliminates confusion.

• Example: In England the word buzzard refers to a hawk, where in the U.S. it refers to a vulture.

• This is called binomial nomenclature. The scientific name of an organism consists of its Genus and species.

• Example: The grizzly bear is Ursus arctos. Many bears belong to the genus Ursus and the grizzly is the only member of the species arctos.

Linnaeus’s System of Classification

• Carolus Linnaeus (1707-1778) was a Swedish botanist and developed the two-word naming system.

• He also came up with the seven level hierarchy of classification still used today. The levels from smallest to largest are species, genus, family, order, class, phylum and kingdom.

• Each level is called a taxon, and the study of classification is called taxonomy.

Kingdoms and Domains• 2 Kingdoms• Linneaeus originally

separated all organisms into only 2 kingdoms; Plants and Animals

5 Kingdoms• Later, as biologists

learned more about the natural world they realized that microscopic organisms, as well as fungi and algae needed their own kingdoms because of their many differences from plants and animals so the 5 kingdoms system was developed; Animalia, Plantae, Fungi, Protista, and Monera (bacteria)

6 Kingdoms• As more evidence

about microorganisms continued to accumulate, biologists came to recognize that the Monera were composed of two distinct groups so many consider them members of two kingdoms, Eubacteria, and Archaebacteria

The Three-Domain System• Domains are groupings

larger than kingdoms. They are:

• Eukarya-contains protists, fungi, plants, and animals

• Bacteria-contains eubacteria

• Archaea-contains the archaebacteria

Characteristics Used to Group Organisms into Kingdoms

• Cell Type - prokaryotic (no nucleus) or eukaryotic (have nuclei)

• Cell Structures - cell wall types, chloroplasts

• Number of Cells – unicellular or multicellular

• Mode of Nutrition – autotrophic or heterotrophic

Identifying Organisms• A dichotomous key is a tool

that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish.

• Keys consist of a series of choices that lead the user to the correct name of a given item. "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.