1
Classification
Classification
 The grouping of objects or information based on similarities
 Taxonomy: the branch of biology that groups and names
organisms based on their different characteristics
 Taxonomists: scientists who study taxonomy
 Carolus Linnaeus (1707-1778) was a Swedish botanist that
developed binomial nomenclature
 Binomial nomenclature: two-word naming system (scientific
name) for different species
 Scientists all over the world can communicate about an
organism using its scientific name, regardless of country,
language, etc.
o Written in Latin because Latin is no longer used and
therefore does not change
o Each scientific name has two words that are italicized or
underlined
 First word: genus name (capitalized)
 Second word: species name (not capitalized)
Homo sapiens
Genus Species
 Scientists classify organisms based on their characteristics
and if they are related through evolution
2
Taxa
 Groups into which living things are classified
 Organisms are organized into 7 taxa
Most broad – has
lots of different
types of organisms
Gets more
specific
Most specific –
has only 1 type of
organism
1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
Remember
King
Philip
came
over
for
good
spaghetti
Six Kingdoms of Living Things
1. Archaebacteria: Bacteria that live in extreme
environments (hot springs)
2. Eubacteria: Common bacteria
3. Protista: Unicellular (Amoeba, Paramecium) and
multicellular eukaryotes (kelp) that lack complex
organ systems and live in moist environments
4. Fungi: Unicellular or multicellular eukaryotes that
absorb nutrients from organic materials in the
environment (Mushrooms, yeast, molds)
5. Animalia: multicellular heterotrophs (animals)
6. Plantae: multicellular eukaryotes that carry out
photosynthesis (plants)
Remember
Archie
Eats
Pretty
Fantastic
Apple
Pies
3
Most broad – has
lots of different
types of organisms
Gets
more
specific
Most specific –
has only 1 type of
organism
4
The Six Kingdoms of Life
Kingdom
Cell type
Organization
Nutrition
Organisms
Archaebacteria Prokaryotic Unicellular-small
Halophiles (love
Absorb,
salt),
Chemosynthesis Thermophiles
(love heat)
Eubacteria
Prokaryotic Unicellular-small
Absorb,
Bacteria,
Photsynthesis
Cyanobacteria
Chemosynthesis
Protista
Eukaryotic
Unicellular or
colonial
Ingest or
Photosynthesis
Amoeba,
Euglena, Algae
Fungi
Eukaryotic
Multicellular
Absorb
Fungi, yeast,
molds
Plantae
Eukaryotic
Multicellular
Photosynthesis
Plants
Animalia
Eukaryotic
Multicellular
Ingest
Animals
Chemosynthesis: Making food using chemicals in the environment
Photosynthesis: Making food using light energy
Decomposers: Organisms that absorb nutrients from dead organisms
Heterotrophs: Organisms that cannot make their own food and must ingest it
Autotrophs: Organisms that can make their own food by chemosynthesis or
photosynthesis
5
How do taxonomists determine if organisms are related by
evolution?
 Similar physical characteristics between organisms
 Similar breeding behavior (mating calls)
 Same geographical location
 Same number and structure of chromosomes
 Similar DNA sequences
Closely related organisms
have more levels of
taxonomy in common……………
…..than unrelated
organisms
6
Phylogeny
 The evolutionary history of a species
 Cladistics: a biological system of classification based on
phylogeny
o As groups of organisms diverge and evolve from a
common ancestor, they keep some of the same traits
(derived traits)
o Cladogram: branching diagram that shows the derived
traits of a group of organisms (like a pedigree that shows
evolution)
o The closer 2 organisms are in a cladogram, the more
probable that they are closely related by evolution
7
Three domains of living things
 Some scientists prefer to classify living things into
domains rather than kingdoms
 These scientists group organisms according to what their
DNA (genes) looks like
 Three domains
1. Archaea: Bacteria that live in extreme environments
(hot springs)
2. Eubacteria: common bacteria
3. Eukarya: organisms whose DNA (genes) is in a nucleus
Remember
Archie
Eats
Eclairs
Domains
Kingdoms
Archaea
Eubacteria
Eukarya
Archaebacteria
Eubacteria
Protista
Fungi
Plantae
Animalia
8



Dichotomous Key
A classification tool that uses paired statements to assist a person in
learning the identity of an organism
It can be written in two different forms, which both give the same
information
o 1. A list of paired statements
o 2. A numbered diagram
For example, we could organize a dichotomous key to classify chickens,
lizards, ducks, and snakes, which are all egg-laying animals
List of paired statements
1a. Feathers
1b. No feathers
Go to 2
Go to 3
2a. Swims
2b. Does not swim
Duck
Chicken
3a. Legs
3b. No legs
Lizard
Snake
2a. Swims
(Duck)
1a. Feathers
2b. Does not
Swim
Numbered Chart
(Chicken)
Egg-laying
animals
3a. Legs
(Lizard)
1b. No feathers
3b. No legs
(Snake)