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, Carl von Linne (aka Carolus Linnaeus) improved the work of previous taxonomists by a) creating a hierarchical classification system based on structural

similarities among organisms to separate them into categories b) developing a scientific name for each organism 3. Binomial Nomenclature ➢ Linnaeus used two words to name each organism

giving each 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) Can invent words 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 (only one is a fish) - cougar, mountain lion, panther (all the same animal) 5.The Linnaean System of Classification ➢ Classified organisms based on structural similarities through 7 levels with his

binomial nomenclature forming the bottom 2 divisions ➢ The levels begin with general characteristics and become more specific as we descend through the categories. (p. 488)

➢ The 7 levels are: Kingdom, Phylum, Class, Order, Family, Genus, Species

Dumb King Phillip Can Only Fight Great Soldiers 6. Modern Classification ➢ Taxonomists have expanded on Linnaeus’ classification system because:

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 (ie. Nutrition) 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

Added by modern

taxonomists

Divided into breeds

or varieties by

modern taxonomists

7. Tools of Classification ➢ Taxonomists use many tools to classify organisms including: Phylogeny,

Molecular Genetics (DNA, RNA) and Dichotomous Keys a) Phylogeny

- refers to the evolution or historical development of any species - can be represented through branching tree diagrams called 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.

Prokaryote – without a nucleus or other membrane-bound organelles Eukaryote – contains membrane- bound nucleus and organelles

➢ Examples: Cladogram for the Phylum Chordata

Phylogenetic Tree of Life

➢ The relationship between the six kingdoms is illustrated in a phylogenetic tree ➢ The ancestor is in the tree “trunk” and organisms that have arisen from it are

placed at the ends of tree “branches” with lengths proportional to the predicted evolutionary time between organisms

b) Dichotomous Keys - are designed to assist people in identifying living things using physical characteristics - consist of a series of choices that lead the user to the correct name of a given item - from “dichotomy” meaning branching or contrasting ideas

= always give two choices in each step - the most common styles of dichotomous keys are: 1. Branching Keys

: each question is like a tree branch that has smaller branches diverging from it

2. Numeric Keys - have questions arranged in couplets

Practice Problems

1. What trait separates Lampreys from tuna this cladogram? ______________________

2. What separates a salamander

from a turtle?

______________

_______________

3. Which organism is most

related to the leopard?

____________________

4. What 4 traits do these two

organisms share?

_____________________

_____________________

_______________________

___________________

5. Which organism will have

DNA most similar to the

turtle?

______________________________________________

6. Which organism’s DNA will differ the most from the leopard?

_____________________________________________

Use the cladogram below to answer the questions on the backside of this worksheet

1. What trait separates amphibians from

primates on this cladogram?

________________

___________________

2. What separates rabbits and primates from

crocodiles on this cladogram?

___________________________

3. What 5 traits do the rabbits and primates

share? ____________________

___________ ____________ _____________

__________

4. Which organism is most related to the bird on this

cladogram?_______________________________________

5. Which organism will have DNA most similar to the bird?

______________________________________________

CCLLAASSSSIIFFIICCAATTIIOONN OOFF LLIIVVIINNGG TTHHIINNGGSS

1. Taxonomy

➢ The branch of biology that deals with the ________________ of living organisms

➢ 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

➢ Aristotle was a Greek philosopher in the 4th century B.C. who developed the first

classification scheme.

= classified organisms as either or using the _____________ they

lived in as a basis for grouping.

➢ In the eighteenth century, Carl von Linnae (aka ___________ ____________) improved

the work of previous taxonomists by

a) creating a ________________ classification system based on ____________

similarities among organisms that separate them into categories.

b) developing a ___________ ___________for each organism

3. Binomial Nomenclature

➢ Linnaeus used two words to name each organism, giving each 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:

_________ _____________ = Modern man; ___________ ___________________ = dog

** These can also be abbreviated (H. sapien, C. familiaris)

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:_________ ____________ = dog, ___________ ___________ = wolf

➢ Eliminates the use of _________ ________which can be confusing and misleading.

Examples:

- jackfish, jellyfish, silverfish, starfish (only one is a fish)

- cougar, mountain lion, panther (all the same animal)

5. The Linnaean System of Classification

➢ Classified organisms based on ________________ ______________ through 7 levels with

Linnaeus’ binomial nomenclature forming the bottom 2 divisions.

➢ These levels begin with _______________ _____________ and become more ___________

as we descend through the categories. (p. 488)

➢ The 7 levels are:____________________________________________________________

Dumb King Phillip Can Only Fight Great Soldiers

6. Modern Classification

➢ Taxonomists have expanded on Linnaeus’ classification system.because

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

Added by modern taxonomists

Divided into breeds or varieties by modern taxonomists

7. Tools of Classification

➢ Taxonomists use many tools to classify organisms including: Phylogeny, Molecular

Genetics (DNA, RNA) and Dichotomous Keys

a) Phelogeny

- refers to the evolution or ___________ ________________of any species

- can be represented through scientific diagrams called_________________

: use _______________ _______________ to determine evolutionary relationships

: the more closely related species are, the more derived characters they will share

- cladograms should not be seen as evolutionary fact, but only as a ________________

__________________ for speciation

Prokaryote – without a nucleus or other membrane-bound organelles Eukaryote – contains membrane- bound nucleus and organelles

Examples:

Cladogram for the Phylum Chordata

Phylogenetic Tree of Life

➢➢ TThhee rreellaattiioonnsshhiipp bbeettwweeeenn tthhee ssiixx kkiinnggddoommss iiss iilllluussttrraatteedd iinn aa____________________________________ ____________________

➢➢ TThhee aanncceessttoorr iiss iinn tthhee ttrreeee ““ttrruunnkk”” aanndd oorrggaanniissmmss tthhaatt hhaavvee aarriisseenn ffrroomm iitt aarree ppllaacceedd aatt tthhee eennddss

ooff ttrreeee ““bbrraanncchheess”” wwiitthh lleennggtthhss pprrooppoorrttiioonnaall ttoo tthhee pprreeddiicctteedd eevvoolluuttiioonnaarryy ____________________

bbeettwweeeenn oorrggaanniissmmss

b) Dichotomous Keys - are designed to assist people in identifying living things using _________ __________ - consist of a series of ____________ that lead the user to the correct name of a given item - from “dichotomy” meaning branching or contrasting ideas

= always give _____ choices in each step - the most common styles of dichotomous keys are: 1. Branching Keys

: each question is like a tree branch that has smaller branches diverging from it

2. Numeric Keys - have questions arranged in couplets