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CHAPTER 1 – CLASSIFIYING AND EXPLORING LIFE
LESSON 2 – CLASSIFYING ORGANISMS
Classifying Living Things
Aristotle, a philosopher in ancient
Greece, was the first to classify living
things.
Categories he used for classifications
 Animals – by shape and size, and
color of blood
 Plants – by structure, size, tree,
shrub, or herb
Determining Kingdoms
 Linnaeus, a Swedish doctor and
botanist living in the 1700s,
classified all organisms into 2
kingdoms.
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 In 1969 Robert H. Whittaker
proposed 5 kingdoms:
o Monera, Protista, Plantae, Fungi,
and Animalia
Determining Domains
Our current classification system is
called systematics.
Characteristics for classification include
 Cell type
 Habitat
 How organism gets food and energy
 Structure and function of features
 Common ancestry and DNA analysis
There are 3 domains and 6 kingdoms.
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Domains and Kingdoms (Table 2, p. 20)
Characteristics
of the Organisms
Domain
Kingdom
Bacteria
Bacteria
simple
unicellular
Archaea
Archaea
simple
unicellular
live in hot or
salty places
Eukaria
Protista
-
unicellular but
more complex
Fungi -
-
unicellular or
multicellular;
absorb food
Plantae
-
multicellular &
make food
Animalia -
multicellular &
take in food
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Some Definitions
species – a group of organisms with
similar traits and are able to produce
fertile offspring.
genus – a group of similar species
Grouping of Organisms
 Kingdoms contain sub-groups.
 Example: the brown bear (see p. 21)
Domain -
-
-
-
-
-
-
- Eukaria
Kingdom
-
-
-
-
-
-
Animalia
Phylum -
-
-
-
-
- Chordata
-
-
-
-
-
Mamalia
Order -
-
-
-
- Carnivora
Family -
-
-
-
Ursidae
Genus -
-
- Ursus
Species
-
Class
Ursus arctos
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Scientific Names
(The system comes from Linneaus.)
Binomial nomenclature gives each
organism a two-word scientific name.
 First name is the genus.
 Second name is the species.
Classification Tools
1. A dichotomous key
 a series of descriptions arranged in
pairs
 useful for identifying an unknown
organism by a process of
elimination
 you need to get the key that suits
the organism
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Examples of Dichotomous Keys
 P. 22 of textbook shows one for
some fish
 Reading Essentials p. 11 shows one
for North American mice
 P. 25 of textbook shows one for
some beetles.
2. A cladogram
 a branched diagram that shows
relationships among organisms,
including common ancestors
 it shows how species are related
 Many have been constructed.
o They appear by exhibits of fossils
in the Museum of Natural History
in NYC
Examples: p. 23 of textbook and
Reading Essentials p. 11