Biological

Classification

Chapter 17

Objective: K3 - Define taxonomy, recognize the importance of a

standardized taxonomic system to the scientific community, & use a dichotomous key to classify an

organism

Finding Order in Diversity• To study the diversity of life,

biologists use a classification system to name organisms and group them in a logical manner.

• Taxonomy - the branch of biology that groups and names organisms based on studies of their different characteristics

• Biologists who study taxonomy are called taxonomists.

Tacitus

bellus

• Classification systems change with expanding knowledge. Populus

tremuloidesQuaking Aspen

Carolus Linnaeus

• Swedish botanist• Developed Binomial Nomenclature

- (Two-word naming system)- Genus»Noun, Capitalized, Underlined or Italicized

- Species»Descriptive, Lower Case, Underlined or Italicized

– Each species is assigned a two-part scientific name

• Exp. Ursus arctos

Carolus von Linnaeus(1707-1778)

Scientist who laid foundation for modern taxonomy

System of Classification

• Linnaeus’s hierarchical system of classification includes seven levels (from largest to smallest)

Grizzly Bear (common name)

– Kingdom Animalia

– Phylum Chordata

– Class Mammalia

– Order Carnivora

– Family Ursidae

– Genus Ursus

– Species arctos

Each of the levels is called

a TAXON

Ursus arctos (scientific name)

• Taxonomic categories pneumonic device–Kingdom King–Phylum Philip–Class Came–Order Over–Family For–Genus Good–Species Soup

System of Classification

www.BioEdOnline.org

Dichotomous Keys Identify Organisms

Dichotomous keys contain pairs of contrasting descriptions.

After each description, the key directs the user to another pair of descriptions or identifies the organism.

Example: 1. a) Is the leaf simple? Go to 2

b) Is the leaf compound? Go to 3

2. a) Are margins of the leaf jagged? Go to 4b) Are margins of the leaf smooth? Go to 5

3. a) Leaflets attached at one central point? Buckeye

b) Leaflets attached at several points? Go to 7

Kingdoms and Domains

• Domain– Most inclusive category – Larger than a kingdom– There are 3

» Eukarya – includes the kingdoms • Protists, Fungi, Plants & Animals

» Bacteria – corresponds to the kingdom Eubacteria» Archaea – corresponds to the kingdom Archaebacteria

www.BioEdOnline.org

Kingdom Fungi

Cell Type: Eukaryotic – most Multicellular / some Unicellular (yeast)

Structure: all have cell walls made of chitin

Obtain nutrients: Heterotrophs (by absorption) – external digestion; breaks down dead or decaying matter

Examples: Mushrooms, Mold, Yeast

www.BioEdOnline.org

Streptococcus mutans(can cause endocarditis and dental caries)

Bacillus anthracis(spores can live in soil for years)

The Kingdom Eubacteria

Common name: Bacteria

Cell Type: Prokaryotic - Unicellular

Structure: All have cell wall with Peptidogylcan

Obtain nutrients: autotroph or heterotroph

Basic shapes are cocci, bacilli, spirilla

Reproduce by binary fission

Examples: E. coli, streptococcus, staphylococcus, lactobacillus

www.BioEdOnline.org

The Kingdom Archaebacteria

Cell Type: Prokaryotic - Unicellular

Structure: All contin cell wall without peptidogylcan

Obtain nutrients: autotroph or heterotroph

Examples: Methanogens—poisoned by O2

Thermaphiles—live in extreme temperatures Halophiles—live in high saline

www.BioEdOnline.org

Entamoeba histolytica

The Kingdom Protista

A classification problem

Cell Type: Eukaryotic –Unicellular or Multicellular

Structure: Some have cell walls, some move with flagella, pseudopods or cilia

Obtain nutrients: Autotrophic (plant-like) and heterotrophic (animal-like)

Examples: Amoeba, paramecium, diatom, euglena

www.BioEdOnline.org

The Kingdom Plantae

Cell Type: Eukaryotic – Multicellular

Structure: cell wall with cellulose

Obtain nutrients: Autotrophs (by the process of photosynthesis which makes glucose)

Examples: Flowers, trees, grass

Sunflowers in Fargo, North Dakota

Ginkgo biloba

Ginkgos are often very long-lived. Some specimens are thought to be more than 3,500 years old.

www.BioEdOnline.org

Colony of sponges

Kingdom Animalia

Cell Type: Eukaryotic – Multicellular

Structure: no cell walls

Obtain nutrients: Heterotrophic (by ingestion – must eat)

Examples: Sponges, reptiles, mammals Txodes scapularis

Deer tick

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Six KingdomsSix Kingdoms