Classification: Organizing Life’s Diversity
At least 1.7 million species of living organisms have been discovered: the list grows longer every
year.
What should we do with them?
How are they to be classified?
18.1 Classification
A. How classification begins
1. Biologists want to better understand organisms so they organize them.
2. One tool that they use to do this is __________________.
a. the grouping of objects or information based on similarities.
3. ________________ is the branch of biology that groups and names organisms based
their different characteristics.
B. Aristotle’s System
1. The Greek philosopher _________________ (384-322 B.C.) developed the first widely
accepted system of biological classification.
2. He classified all the organisms he knew into two groups: ________________
________________________.
3. According to his system, birds, bats, and flying insects are classified together even
though they have little in common besides the ability to fly.
C. Linnaeus’s System
1. In the late eighteenth century, a Swedish botanist, ______________________ (17071778), developed a method of grouping organisms that is still used by scientists today.
2. Based on _____________ and __________________ similarities of organisms.
3. As a result, the groupings revealed the relationships of the organisms.
4. Linnaeus developed a two-word naming system called __________________
____________________ to identify _________________.
5. Each species is assigned a two part scientific name.
6. Scientific names are always written in _____________________.
7. The first word is capitalized and the second word is lowercase.
Homo sapiens
8. The first part of the scientific name is the _________________
9. The second part of the scientific name is the _____________________
Do Ursus arctos and Ursus maritimus belong to the same species or to the same genus?
10. Linnaeus’s hierarchical system of classification includes seven levels.
11. Each of these levels is called a _________________.
From smallest to largest
12. ______________ – organisms that look alike and successfully interbreed ; the
smallest and most specific of the taxonomic categories
13. ______________ – the largest and most inclusive of the taxonomic categories
D. Scientific and common names
1. Taxonomists are required to use _____________________
The language is no longer used in conversation and it does not change.
Why do scientists use Latin names for classification?
Taxonomic Categories
Kingdom (most broad)
Phylum
Class
Order
Family
Genus
Species (most specific)
Which taxon contains the others?
Order
Class
Genus
Family
F. Taxonomy: A useful tool
1. Remember taxonomy is the _________________________________________
2. Some biologists use a ______________________________________________
3. A Dichotomous Key is made up of a set of paired numbered statements. Each set deals
with a single characteristic of an organism, such as leaf shape or arrangement.
3. By following the key, a specific organism can be identified based on characteristics.
1. Example:
Scientists have discovered quite a few new creatures on planet Pamishan. They need your
help to identify and classify them. Use the dichotomous key on the next page to identify
these creatures.
a.
a.
b.
c.
d.
f.
______________
______________
______________
______________
b.
g.
______________
______________
______________
______________
d.
c.
h.
e.
f.
g.
h.
i.
______________
______________
______________
______________
e.
j.
______________
______________
______________
______________
A Key to New Pamishan Creatures
1.
a. The creature has a large wide head...................................go to 2
b. The creature has a small narrow head..............................go to 11
2.
a. It has 3 eyes .....................................................................go to 3
b. It has 2 eyes ....................................................................go to 7
3.
a. There is a star in the middle of its chest..........................go to 4
b. There is no star in the middle of its chest ......................go to 6
4.
a. The creature has hair spikes ...........................................Broadus hairus
b. The creature has no hair spikes......................................go to 5
5.
a. The bottom of the creature is arch-shaped ....................Broadus archus
b. The bottom of the creature is M-shaped .......................Broadus emmus
6.
a. The creature has an arch-shaped bottom .......................Broadus plainus
b. The creature has an M-shaped bottom...........................Broadus tritops
7.
a. The creature has hairy spikes .......................................go to 8
b. The creature has no spikes............................................go to 10
8.
a. There is a star in the middle of its body ......................Broadus hairystarus
b. The is no star in the middle of its body .......................go to 9
9.
a. The creature has an arch shaped bottom ......................Broadus hairyemmus
b. The creature has an M shaped bottum ..........................Broadus kiferus
10. a. The body is symmetrical ..............................................Broadus walter
b. The body is not symmetrical........................................Broadus anderson
11. a. The creatrue has no antennae .......................................go to 12
b. The creature has antennae ...........................................go to 14
12. a. There are spikes on the face ........................................Narrowus wolfus
b. There are no spikes on the face ..................................go to 13
13. a. The creature has no spike anywhere ..........................Narrowus blankus
b. There are spikes on the right leg ................................Narrowus starboardus
14. a. The creature has 2 eyes...............................................go to 15
b. The creature has 1 eye...............................................Narrowus cyclops
15. a. The creature has a mouth..........................................go to 16
b. The creature has no mouth........................................go to 17
16. a. There are spikes on the left leg ................................Narrowus portus
b. There are no spikes at all .........................................Narrowus plainus
17. a. The creature has spikes ............................................go to 18
b. The creature has no spikes .......................................Narrowus georginia
18. a. There are spikes on the head ....................................go to 19
b. There are spikes on the right leg................................Narrowus montanian
19. a. There are spikes covering the face ............................Narrowus beardus
b. There are spikes only on the outside edge of head ....Narrowus fuzzus
What is a dichotomous key?
________________________________________________________________________
Evidence to Classify Organisms
1. __________________________________
2. __________________________________
3. __________________________________
4. __________________________________
1. Physical characteristics
a. Structural similarities among species reveal relationships
b. The presence of many shared physical structures implies that species are
closely related and may have evolved __________________________________.
2. Behavioral – breeding behavior
a. Two species of frogs, Hyla versicolor and Hyla chrysoscelis live in the same
area and look similar
b. During the breeding season there is an obvious difference in their mating
behavior – different __________________ between the calls
3. Chromosomes
a. Both the number and structure of ___________________, as seen during
mitosis and meiosis, provide evidence about relationships among species.
4. DNA/Biochemistry
a. Closely related species have similar DNA sequences and therefore proteins
b. In general, the more inherited nucleotide sequences that two species share, the
more ______________________________.
Which of the following is NOT a way to determine evolutionary relationships?
A. DNA
B. Chromosomes
C. Taxon
D. Behavioral
A. Evolutionary Classification
1. Biologists group organisms into categories that represent lines of evolutionary
descent, or phylogeny, not just physical similarities
The evolutionary history of a species is called its ____________________
B. Phylogenetic Classification: Models
1. _____________________ – system of classification based on phylogeny
a. Characteristics and organisms can be organized on a tree-like model
b. Starts with a common ancestor
c. Groups of organisms diverge from the ancestor
d. Nodes are where the organisms branch off – these are anatomical
relationships like backbones, tails, etc
e. All of the organisms have the trait after the node
f. Shown on a ______________________
14.2 The Six Kingdoms
C. The Six Kingdoms of Organisms
Three main characteristics that distinguish the members of each kingdom
a. ______________________________
b. ______________________________
c. ______________________________
What three main characteristics distinguish the members of the six kingdoms?
Type of cell
How they obtain their food
Number of cells
SIX KINGDOMS
ARCHAEBACTERIA (Prokaryotes)
EUBACTERIA (Prokaryotes)
PROTISTS (Eukaryotes)
FUNGI (Eukaryotes)
PLANTS (Eukaryotes)
ANIMALS (Eukaryotes)
Prokaryotic Kingdoms
_____________ - organisms with cells that lack a nuclei bounded by a membrane
Originally the two bacteria were grouped together in one kingdom called Monera.
Now they are separated into two kingdoms: Archaebacteria and Eubacteria
Kingdom ________________________
A. Prokaryotic with cell walls
1. Unicellular
2. Chemotrophic, Autotrophic or Heterotrophic
B. Found in _________________________ environments
1. Swamps, deep-ocean hydrothermal vents
2. Oxygen free environments
Examples: halobacterium, methanogens and thermoacidophiles
Kingdom ___________________
(Streptococcus pneumoniae)
A. Prokaryotic with cell wall
1. Unicellular
2. Autotrophic or Heterotrophic
B. Most species of bacteria are in this kingdom
C. Live in ____________________________
D. Some cause diseases
1. Strep throat and pneumonia
E. Most are harmless and many may be helpful
Kingdom __________________
(slime molds and algae)
A. Eukaryotic with a cell wall
1. Most are unicellular, some are multicellular
2. Lacks complex organ systems
3. Autotrophic and/or Heterotrophic
B. Lives in _________ environments
C. Members are very different from one another
1. Some are plantlike (______________)
2. Some are animal-like (_______________)
3. Some are fungus-like (_________________)
Kingdom ____________
(mushrooms, mold and mildew)
A. Eukaryotic with cell walls made of ___________
1. Most are multicellular, some are unicellular
2. External heterotrophs; ____________________
Kingdom ________________
(Ferms, Angiosperms)
A. Eukaryotic with cell walls made of cellulose
1. All multicellular
2. Autotrophs and photosynthetic
3. No species can move from place to place.
B. ______________________________
C. Range from tiny mosses to giant trees
Kingdom Animalia
(Invertebrates and Vertebrates)
A. Eukaryotic with no __________________
1. Multicellular with complex cells
2. Heterotrophs with specialized organ systems
B. _________________________
C. Nearly all are able to move from place to place.
Six Kingdoms Summary
Kingdoms Archaebacteria and Eubacteria contain only unicellular prokaryotes.
Kingdom Protista contains eukaryotes that lack complex organ systems.
Kingdom Fungi includes heterotrophic eukaryotes that absorb their nutrients.
Kingdom Plantae includes multicellular eukaryotes that are photosynthetic.
Kingdom Animalia includes multicellular, eukaryotic heterotrophs with cells that lack
cell walls.
Which of the following describes a fungus?
A. autotrophic prokaryote
B. unicellular or multicellular heterotroph
C. unicellular autotroph
D. heterotrophic prokaryote