Chapter 17
Biological
Classification
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.
• Classification systems change with
expanding knowledge.
Tacitus bellus
Populus tremuloides
Quaking 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
– Phylum
– Class
– Order
– Family
– Genus
– Species
Animalia
Chordata
Mammalia
Each of the
levels is called
a TAXON
Carnivora
Ursidae
Ursus
arctos
Ursus arctos
(scientific name)
System of Classification
• Taxonomic categories
–Kingdom
–Phylum
–Class
–Order
–Family
–Genus
–Species
pneumonic device
King
Philip
Came
Over
For
Good
Soup
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 4
b) 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
www.BioEdOnline.org
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
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
The Kingdom Eubacteria



Common name: Bacteria
Streptococcus mutans
(can cause
endocarditis and
dental caries)
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
Bacillus anthracis
(spores can live in
soil for years)
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
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)
Entamoeba histolytica
Examples: Amoeba, paramecium, diatom,
euglena
www.BioEdOnline.org
The Kingdom Plantae




Cell Type: Eukaryotic –
Multicellular
Structure: cell wall with cellulose
Sunflowers in
Fargo, North Dakota
Obtain nutrients: Autotrophs (by
the process of photosynthesis
which makes glucose)
Examples: Flowers, trees, grass
Ginkgo biloba
Ginkgos are often
very long-lived.
Some specimens are
thought to be more
than 3,500 years old.
www.BioEdOnline.org
Kingdom Animalia




Cell Type: Eukaryotic –
Multicellular
Colony of sponges
Structure: no cell walls
Obtain nutrients:
Heterotrophic (by ingestion –
must eat)
Examples: Sponges, reptiles,
mammals
Txodes scapularis
Deer tick
www.BioEdOnline.org
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Six Kingdoms
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Classification - Pearland Independent School District