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