• To group things based on similarities

• Ex: seating at assemblies, food in the
  grocery store, classes at KHS
 History of Classification
• Aristotle – Greek – divided
  organisms into 2 large Kingdoms
 1. Plant
 2. Animal
Then he further divided them based on –
Animals: where they lived
Plants: size and structure

What are some problems with Aristotle’s
• The science of classifying and naming
           Carl Linnaeus
• Swedish – created a system based on
  similarities in body structure and
  systems, size, shape, color and methods
  of obtaining food

The father of modern plant and
animal classification (1707-1778)
      Taxonomic Categories
• Linnaeus placed organisms into related
  groups called taxa (taxon-singular) based
  on their morphology (similar structure &
• The broadest taxon is called the kingdom
• Each taxa is a proper noun & should be
  capitalized except species

• Each level or taxon groups together
  organisms that share more characteristics
  than the level above
           Linaeus’ System
•       Gives a 2 word name to every organism
•       Called Binomial nomenclature – two
    –     1st word -- Genus
    –     2nd word – species
    –     These together = scientific name
Example: Canis familiaris (domesticated
Homo sapien (Human)
Branta canadensis (canada goose)
----- always underlined or in italics
----- Genus is the first word and is capitalized
Five – Kingdom System
• Aristotle and Linnaeus use only
  characteristics that were easily
• Today, scientists also use chemical
  make-up, similarities in genes and
  body structure, fossils and
  development of the embryo
• The smallest, most precise category of
• Organisms in the same species can
  breed and produce fertile offspring
• Horse + donkey = mule
• Mule + mule = ????
   Definition of a mule

A mule is a cross between two species of
equine: the horse or pony (Equus caballus)
and the domestic donkey (Equus asinus).
The word 'mule' is used for either the cross
of male donkey on female horse or female
donkey on male horse, although the latter
cross is more correctly known as a 'hinny'.
• Use the term division instead of
  phylum for classifying plants

• Plant species are subdivided into
  varieties, while bacteria are
  subdivided into strains
    Characteristics used
•   Presence of a nucleus
•   Single celled or many celled
•   The ability to make food
•   And the ability to move
         Prokaryotic cells
• simple in structure- no organelles
• Contains genetic material but no
  organized nucleus or membrane
  bound organelles.
• Small in size
       Eukaryotic Cells
• Contain a nucleus and a membrane bound
  organelles. This includes cells of all the
  other kingdoms.
Two Kingdom System         Five Kingdom System          Three Domain System

Animals                    Animalia
(includes non-
photosynthetic protists,                                (containing a nucleus)
such as protozoans)

(includes photosynthetic   Plantae
protists, such as algae)
                               eukaryotic organisms,

                           microscopic—like our pond

                           Monera                       Bacteria
                           (prokaryotes—lack a
                           nucleus and have very        Archaea
                           simple cellular structure)
Modern Taxonomic System
1. Domain Archae
2. Domain Bacteria
3. Domain Eukarya
 1.   Kingdom Protista
 2.   Kingdom Fungi
 3.   Kingdom Plantae
 4.   Kingdom Animalia
     Domain Bacteria
• (Kingdom Eubacteria)
• Contains all other bacteria including
  those causing disease
    Domain Archaea
• (Kingdom Archaebacteria)
• Contains chemosynthetic bacteria
  living in harsh environments
        Archae & Bacteria
• Are unicellular
• Prokaryotes lacking a nucleus
• Live in harsh environments like very
  salty lakes; intestines of mammals;
  and hot, sulfur spring
• May be autotrophs or heterotrophs
• Bacteria and Archaea are both prokaryotic

     Domain Bacteria      Domain Archaea

                                           Figure 1.8.2
      Domain Eukarya
Contains all eukaryotic organisms

•   Kingdoms Protista
•   Kingdom Fungi
•   Kingdom Plantae
•   KingdomAnimalia
• These all contain a nucleus and membrane-
  bound organelles
• All members of Plantae & Animalia are
  multicellular organisms
• Fungi and Animalia are heterotrophs,
• Plantae are capable of making their own
• Eukarya
  includes at                      Domain Eukarya

  least four
– Protista
                Kingdom Protista             Kingdom Plantae

– Plantae
– Fungi
– Animalia      Kingdom Fungi                Kingdom Animalia

                                                               Figure 1.8.3
• Mainly unicellular with a few
  multicellular organisms
• may be autotrophic (Euglena) or
  heterotrophic (Ameba)
• Absorptive heterotrophs ( digest food
  & then absorb it)
• Include
  – multicellular mushrooms,
  – mold,
  – unicellular yeast
• Are ingestive heterotrophs that take in food
  & then digest it inside their multicellular
• Includes all plants and are the only all
  multicellular, autotrophic kingdom
     Groups within Kingdoms
• All organisms are    •   Kingdom
  put into groups.
• Each grouping of
                       •   Phylum
  organisms have       •   Class
  more in common
  and fewer            •   Order
  organisms (the       •   Family
  closer you get to
  the species group)   •   Genus
                       •   Species

• The other six taxa from broadest
  to most specific are – Phylum,
  Class, Order, Family, Genus, &
• King Phillip Came Over For
  Gooseberry Soup
Two Kingdom System         Five Kingdom System          Three Domain System

Animals                    Animalia
(includes non-
photosynthetic protists,                                (containing a nucleus)
such as protozoans)

(includes photosynthetic   Plantae
protists, such as algae)
                               eukaryotic organisms,

                           microscopic—like our pond

                           Monera                       Bacteria
                           (prokaryotes—lack a
                           nucleus and have very        Archaea
                           simple cellular structure)
  Common Names & Scientific
• Why use scientific names rather than
  common names?
• Prevents confusion! Many common
  names do not describe the organism
• Example: Starfish, Seahorse, Prairie
• Some organisms have more than one
  common name
• Example: Hognose snake, a.k.a. Puff
  adder, a.k.a. Hoop snake, a.k.a
  Possum snake
 Functions of Scientific Names
1. Help biologists avoid errors in
   communication. The names are the
   same around the world.
2. Organisms with similar evolutionary
   histories are classified together.
   Because of this, organisms that share
   the same genus name are more
   closely related than those that don’t
3. The scientific name gives descriptive
   information about the species (Quercus
   alba – white oak, Q. rubra (red oak)

4. The scientific names allow information
   about organisms to be organized and
   found easily and efficiently.
  Basis for Modern taxonomy
• Modern taxonomists classify organisms
  based on their evolutionary relationships

• Homologous structures have the same
  structure, but different functions & show
  common ancestry
    Homologous Structures
• The bones in a bat’s wing, human’s
  arm, penguin’s flipper are the same
  (homologous), but the function is
     Analogous structures
• Have the same function, but different
  structures & do not show a close
  relationship (insect wing & bird’s
     Embryo development
• Similarity in embryo development shows a
  close relationship (vertebrate embryos all
  have tail & gill slits)
      DNA and Proteins
• Similarity in DNA and amino acid
  sequences of proteins show related
• Evolutionary history
• Are branching diagrams showing how
  organisms are related
• Also called family trees
• Fossil records help establish relationships
  on a phylogenetic tree
• Organizes living things based on their
  evolution (systematics)
• Common ancestor is shown at the base of
  the tree
• Most modern organisms shown at tips of
• Each time a branch divides into a smaller
  branch, a new species evolves
•    Shows how organisms are related
     based on:

    1. Shared characteristic
    2. Derived characteristics such as: feathers,
       hair, scales, etc.
     Dichotomous Keys
• Biologists classify organisms by using
  more detailed lists of traits called
  dichotomous keys.

• They are arranged in steps with two
  descriptive statements at each step

• To use the key, you must always begin
  with a choice from the first pair of
         Dichotomous cont.
• At the end of each description is either
  the name of a species or directions to
  go on to another step

• If you use the key properly, you will
  eventually wind up with the correct
  scientific name of your species.
• Field guides often use descriptions, such as
  the external characteristics of organisms
  and information about the places they can
  be found to help identify them.
An Artificial Key to Some of the Common
Prairie Plants of Southwest Missouri and
            Southeast Kansas

Key to Sections
A. Flowers not white..................................Section A

A1. Flowers cream, yellow, or orange......Section B
A2. Flowers pink or red..........................Section C
A3. Flowers blue or purple......................Section D
A4. Flowers green...................................Section E
                             Section C
                          Flowers Pink or Red
01.Stems square---Wild Bergamont
01. Stems round---02
       02. Leaves opposite---03
       02. Leaves alternate or whorled---04
              03. Inflorescence an umbel; leaves narrowly
              03. Inflorescence terminal; leaves mostly oval-
                  04. Leaves compound---05
                  04. Leaves simple---07
                      05. Stems with prickles---06
                      05. Stems without prickles---Goat's Rue
                               06. Leaflets 8 or more per leaf---
                                     Sensitive Briar
                                      06. Leaflets 7 or less per
                                     leaf---Prairie Rose

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