Chapter 18: Classification
I. Section I: The Importance of Classification
A. The Need for Systems
1. How many species have been named & classified by scientists?
1.7 million
2. What is taxonomy? Classification of living organisms into
different catagories.
3. Why do scientists use taxonomy to name & classify organisms?
To organize all living things; have a universal system of naming
things.
4. What is the problem with using the common names of species?
Give an example. One organism may have several common
names: EXAMPLE – cougar, puma, mountain lion, bob cat,
jaguar, panther
Or one common name may be used for several different
organisms: EXAMPLE – The term “panther” may be used as the
common name for several big cats.
B. Use the Internet to answer the following question:
 Who was Aristotle, where was he from & during what time
period did he live? Greek philosopher who lived from 384 –
322 BC.
 How did Aristotle classify organisms? According to where they
lived &/or what characteristics they had. Plants were
classified according to the type of stem they had (herbaceous
vs. woody) & animals by where they lived (air, water, land).
This got to be confusing because some organisms lived in
several environments or plants had both types of stems.
C. Scientific Nomenclature
1. What does “poly” mean? many
What does “nomen” stand for? name
What are polynomials? Many names; old way of classifying gave
some organisms several names (too confusing).
2. Define the term “genus”. Taxonomic group used to group similar
species. Ex: Genus Panthra
3. In the 1750’s, what did the Swedish biologist Carl Linnaeus
develop? A new system of classification based on a 2 word
naming system known as “binomial nomenclature”. We still use
this system today.
4. Define the term “binomial nomenclature”.
Two word naming system
5. The scientific name for the European honeybee is Apis mellifera;
which term is the genus name? Apis
The species name? mellifera
What does the term “mellifera” mean? “honey”
6. What is your genus & species name? Homo sapiens
7. No 2 species share the same genus & species names.
8. How is the genus name of an organism always written?
Must begin with a capital letter.
How is the species name of an organism always written? Must
begin with a lower case letter.
How should the scientific name be typed? Italicized or in italics
D. The Linnaean System
1. What did Linnaeus base his system of classification on?
Categories based on similarities.
2. What were Linnaeus original kingdoms?
Plants & Animals
3. Identify the 8 basic levels of modern classification:
a. Domain – 3 domains: Bacteria, Archea, Eukarya
b. Kingdom – 6 kingdoms: Eubacteria, Archeabacteria, Protists,
Fungi, Plants, Animals
c. Phylums – subdivisions of the kingdom
d. Classs - subdivisions of the phylum
e. Order - subdivisions of the class
f. Family - subdivisions of the order
g. Genus - subdivisions of the family
h. species - subdivisions of the genus; most specific
4. How many levels of classification do a lion & leopard have in
common? seven
E. Levels of the Modern Linnaean System
1. List the levels of classification & define each level below. – See
above
a.
b.
c.
d.
e.
f.
g.
h.
2. Classification of Humans.
a. Domain - Eukarya
b. Kingdom - Animalia
c. Phylum – Chordata
d. Class - Mammalia
e. Order - Primates
f. Family - Hominidae
g. Genus - Homo
h. species – sapiens
3. What does the scientific name Homo sapiens mean?
Homo = man
sapiens = wise
4. Classification of the Gorilla.
a. Domain - Eukarya
b. Kingdom - Animalia
c. Phylum – Chordata
d. Class - Mammalia
e. Order - Primates
f. Family - Hominidae
g. Genus - Gorilla
h. species – gorilla
II. Section 2: Modern Systematics – (Just read through this section)
III. Section 3: Kingdoms & Domains
A. Updating Classification Systems
1. Into which kingdom were sponges first placed? plants
Why were they classified this way? Because they are attached to the
sea floor.
What invention caused sponges to be reclassified? microscope
Why were they reclassified? Their cells resembled animal cells, not
plant cells.
2. What 2 kingdoms were added to the classification system in the
1800’s? Protista and Monera
3. How many kingdoms were used in the 1950’s? FIVE
Name them: Monera, Protista, Fungi, Plants, Animals
4. What did taxonomists do with kingdom Monera in the 1990’s?
Split it into 2 new categories; Archeabacteria & Eubacteria
5. How many kingdoms do we have today? Six Name them:
Archeabacteria, Eubacteria, Protista, Fungi, Plants, & Animals
B. The 3-Domain System
1. How many domains are there? Three
Name them:
Bacteria, Archea, Eukarya
2. Major characteristics of the 3 domains: Explain each one.
 Cell Type: Either prokaryote (no nucleus) or eukaryote (nucleus)
 Cell Walls: Cells may either peptidoglycan & cellulose
cell walls or lipids cell wall.
 Body Type: The organism is either unicellular or multicellular
 Nutrition: Organism obtains nutrients by making them from
inorganic materials (autotroph) or gets nutrients by eating
other organisms (heterotroph)
 Genetics: Related groups of organisms will have similar DNA,
RNA, & proteins.
3. The 3 Domains
a. Domain: Bacteria
 Common Name - bacteria
 Bacteria are prokaryotes with a strong exterior/outer cell
wall & unique genetic system.
 Bacteria have the same kind of cell membrane lipids as
most eukaryotic cells.
 Bacteria are the most abundant organisms
on Earth & are found in almost every environment.
b. Domain: Archea
 Common Name - archea
 Archea cell wall, cell membrane, & DNA is different from
Bacteria.
 Archea are more similar to eukaryotes.
 Some Archea eventually gave rise to eukaryotes.
 Where are most Archea bacteria found?
In harsh environments such as salt lakes, deep in the
ocean, in hot springs whose temperatures exceed 100 oC.
 What is the term for archea that live in extreme
environments? extremophiles
 What do we call archea that live in environments without
oxygen? anaerobic
c. Domain: Eukarya
 What 4 kingdoms are in this domain? Fungi, Plants,
Animals, Protists
 All members of Eukarya are eukaryotes & have cells with a
nucleus & organelles.
 Most eukaryotes reproduce sexually.
4. Characteristics of the Four Eukaryotic Kingdoms
a. Kingdom: Plantae
 Method of obtaining nutrition: photosynthesis

Where in the plant cell does this process occur? chloroplasts
 Autotrophs or heterotrophs? : autotrophs
 Cell wall made of what carbohydrate? cellulose
 How many known species of plants are there? About 270,000
b. Kingdom: Animalia
 Autotrophs or heterotrophs? heterotrophs
 Unicellular or multicellular? multicellular
 Are they made of tissues, organs, &/or organ systems? Yes
 Do they have a cell wall? No
 How many known species of animals are there? More than one
million
c. Kingdom: Fungi- mushrooms, yeast, molds
 Autotrophs or heterotrophs? : heterotrophs
 Unicellular or multicellular? : multicellular
 Rigid cell wall made of carbohydrate chitin
 More closely related to animals than any other kingdom.
 How many known species of fungi are there? Over 70,000
d. Kingdom: Protista
 Some are autotrophs, like the Euglena, while others are
heterotrophs, like the Amoeba & Paramecium.
 Unicellular or multicellular? Unicellular (one-celled organism)
 NO cell wall. Many protists are surrounded by a flexible
pellicle outside the cell membrane.
5. Name all 6 kingdoms; which are prokaryotes & which are eukaryotes
a. Archeabacteria - prokaryotes: don’t have a nucleus or organelles
b. Eubacteria - prokaryotes: don’t have a nucleus or organelles
c. Protists - eukaryotes: have a nucleus and organelles
d. Fungi - eukaryotes: have a nucleus and organelles
e. Plants - eukaryotes: have a nucleus and organelles
f. Animals - eukaryotes: have a nucleus and organelles