classification of living things · classification of living things 1. taxonomy the branch of...
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CLASSIFICATION OF LIVING THINGS
1. Taxonomy
The branch of biology that deals with the classification of living organisms
About 1.8 million species of plants and animals have been identified. Some
scientists estimate that there may be as many as 5 - 50 million species!
How do we keep track of them all?
2. History of Classification
Aristotle was a Greek philosopher in the 4th century B.C. who developed the
first classification scheme.
Classified organisms as either plants or animals using the environment they
lived in as a basis for grouping.
In the eighteenth century, a Swedish botanist, Carl von Linne improved the
work of previous taxonomists and created a classification system based on
structural similarities among organisms that separate them into categories.
He developed scientific names for each organism in Latin & disposed of
common names. He even “Latinized” his name to Carolus Linnaeus to sell his
idea!
Linnaeus used two words to name each organism, thus his naming system is
known as binomial nomenclature.
3. Naming Organisms
Linnaeus named each organism with a genus name followed by a species name.
a) Genus Name
- Is the first part of the name of an organism
- Is always a noun
- Always begins with a CAPITAL letter.
b) Species Name
- Is the second part of the name
- Is always an adjective
- Always begins with a small letter
- **The genus and species name is always italicized or underlined
Examples:
Homo sapien = modern man; Canis familiaris = dog
** These can also be abbreviated (H. sapien, C. familiaris,)
4. Why Use Scientific Names?
Because they are in Latin
a) It is a dead language
b) It is the universal language of scholars
c) It has many descriptive words
d) Words can be invented for newly discovered
organisms
e) Impossible to duplicate a name
Relationships between organisms are obvious from
their names.
Examples: Canis familiaris = dog, Canis lupus = wolf
Eliminates the use of common names which can be confusing and misleading.
Examples:
jackfish, jellyfish, silverfish, starfish (1st is the only fish)
cougar, mountain lion, panther (all the same animal)
5.The Linnaean System of Classification
Organisms are classified based on structural similarities through 7 levels
with Linnaeus’ binomial nomenclature forming the bottom 2 divisions.
The 7 levels are: Kingdom, Phylum, Class, Order, Family, Genus, Species
These levels begin with general characteristics and become more specific as
we descend through the categories. (p. 488)
6. Modern Classification
Taxonomists have expanded on Linnaeus’ classification system.
Why?
a) Linneaus’ system does not take into account convergent evolution
b) As scientists discovered new organisms their ideas about what
characteristics are important in classifying organisms changed.
c) Technological advances have allowed scientists to compare organisms on the
molecular level to determine similarities. (ie. DNA, amino acids)
Based on molecular evidence organisms are now classified into 3 domains:
Bacteria, Archaea, and Eukarya
Within these domains are 6 kingdoms based on cell type, structure, and
nutrition: Archaebacteria, Bacteria, Protista, Fungi, Plants, and Animals
Prokaryote – without a nucleus or
other membrane-bound organelles
Eukaryote – contains membrane-
bound nucleus and organelles
The 6 Kingdoms
Number of
Cells Energy Cell Type Examples
Archaebacteria Unicellular some autotrophic, most
chemotrophic prokaryote "extremophiles"
Eubacteria Unicellular autotrophic and
heterotrophic prokaryote bacteria, E. coli
Protista most
unicellular heterotrophic or autotrophic eukaryote
ameba, paramecium,
algae
Fungae most
multicellular Heterotrophic eukaryote mushrooms, yeast
Plantae Multicellular Autotrophic eukaryote trees, grass
Animalia Multicellular Heterotrophic eukaryote humans, insects,
worms
7. Phylogeny
The term phylogeny refers to the evolution or historical development of any
species. This development can be represented through scientific diagrams
called cladograms.
Cladograms use derived characters to determine evolutionary relationships
- the more closely related species are, the more derived characters they will
share (p. 495)
Cladograms should not be seen as evolutionary fact, but only as a possible
path for speciation.
Example: Cladogram for the Phylum Chordata
The relationship between the six kingdoms is illustrated in a phylogenetic
tree, a branching cladogram that shows relationships between species from
an evolutionary perspective.
The ancestor is in the tree “trunk” and organisms that have arisen from it
are placed at the ends of tree “branches.”
Branch lengths are proportional to the predicted evolutionary time between
organisms. (p. 503)
CCLLAASSSSIIFFIICCAATTIIOONN OOFF LLIIVVIINNGG TTHHIINNGGSS
1. Taxonomy
The branch of biology that deals with the ________________________________
About ____________ species of plants and animals have been identified. Some scientists
estimate that there may be as many as _____________ species! How do we keep track of
them all?
2. History of Classification
__________ was a Greek philosopher in the 4th century B.C. who developed the first
classification scheme.
Classified organisms as either or using the _______________________ as a
basis for grouping.
In the eighteenth century, a Swedish botanist, ________ improved the work of
previous taxonomists and created a classification system based on ____________ similarities
among organisms that separate them into categories.
He developed _______________for each organism in Latin and disposed of ______________.
He even “Latinized” his name to to sell his idea!
Linnaeus used two words to name each organism, thus his naming system is known as
____________________________.
3. Naming Organisms
Linnaeus named each organism with a name followed by a name.
a) Genus Name
- Is the part of the name of an organism
- Is always a ____________
- Always begins with a ___________ letter.
b) Species Name
- Is the ______________ part of the name
- Is always an ______________
- Always begins with a __________ letter
**The genus and species name is always italicized or underlined
Examples:
__________________________________________________
** These can also be abbreviated (H. sapien, C. familiaris, C. lupus)
4. Why Use Scientific Names?
Because they are in Latin
a) It is a _________ language
b) It is the ______________ language of scholars
c) It has many ______________________
d) Words can be ________________ for newly discovered organisms
e) ___________ to duplicate a name
______________ between organisms are obvious from their names.
Examples:_____________________________________________________
Eliminates the use of ________________which can be confusing and misleading.
Examples:
_________________________________________
_________________________________________
5. The Linnaean System of Classification
Organisms are classified based on _________________________ through 7 levels with
Linnaeus’ binomial nomenclature forming the bottom 2 divisions.
The 7 levels are: _____________________________________________________________
These levels begin with _____________________________ and become more ___________
as we descend through the categories. (p. 488)
6. Modern Classification
Taxonomists have expanded on Linnaeus’ classification system.
Why?
a) Linneaus’ system does not take into account __________________________
b) As scientists discovered new organisms their ideas about what characteristics are important in
classifying organisms changed.
c) Technological advances have allowed scientists to compare organisms on the ______________
to determine similarities. (ie. DNA, amino acids)
Based on ______________________ organisms are now classified into 3 domains:
Bacteria, Archaea, and Eukarya
Within these domains are 6 kingdoms based on__________________________________:
Archaebacteria, Bacteria, Protista, Fungi, Plants, and Animals
Prokaryote – without a nucleus or other membrane-bound organelles Eukaryote – contains membrane- bound nucleus and organelles
The Six Kingdoms
Number of
Cells Energy Cell Type Examples
Archaebacteria unicellular some autotrophic, most
chemotrophic prokaryote "extremophiles"
Eubacteria unicellular autotrophic and
heterotrophic prokaryote bacteria, E. coli
Protista most
unicellular
heterotrophic or
autotrophic eukaryote
ameba, paramecium,
algae
Fungae most
multicellular heterotrophic eukaryote mushrooms, yeast
Plantae multicellular autotrophic eukaryote trees, grass
Animalia multicellular heterotrophic eukaryote humans, insects,
worms
7. Phylogeny
The term phylogeny refers to the evolution or _______________of any species. This
development can be represented through scientific diagrams called_________________.
Cladograms use ________________________________ to determine evolutionary
relationships
- the more closely related species are, the more derived characters they will share (p. 495)
Cladograms should not be seen as evolutionary fact, but only as a ______________for
speciation.
Example: Cladogram for the Phylum Chordata
TThhee rreellaattiioonnsshhiipp bbeettwweeeenn tthhee ssiixx kkiinnggddoommss iiss iilllluussttrraatteedd iinn aa____________________________________,, aa
bbrraanncchhiinngg ccllaaddooggrraamm tthhaatt sshhoowwss rreellaattiioonnsshhiippss bbeettwweeeenn ssppeecciieess ffrroomm aann __________________________________
ppeerrssppeeccttiivvee..
TThhee aanncceessttoorr iiss iinn tthhee ttrreeee ““ttrruunnkk”” aanndd oorrggaanniissmmss tthhaatt hhaavvee aarriisseenn ffrroomm iitt aarree ppllaacceedd aatt tthhee
eennddss ooff ttrreeee ““bbrraanncchheess..””
BBrraanncchh lleennggtthhss aarree pprrooppoorrttiioonnaall ttoo tthhee pprreeddiicctteedd eevvoolluuttiioonnaarryy ____________________ bbeettwweeeenn
oorrggaanniissmmss..
Example: Phylogenetic Tree of Life