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)

Example: Phylogenetic Tree of Life

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