CHAPTER 18CLASSIFICATIO

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18.1 Finding Order in Diversity •Classification – grouping of objects or information based on similarities

•Taxonomy – branch of biology for grouping and naming organisms

Assigning Scientific Names

•Scientific Names are written in Latin because:

• The language is no longer used

• The words stay the same and cannot change since the language is dead

• The words only have one meaning

Early efforts at naming organisms

•Aristotle

• Developed the first method of classification

• Grouped them into 2 groups: plants and animals

• His system was useful but did not group organisms according to their evolutionary history

• Linneaus

• Developed binominal nomenclature system

• Binominal Nomenclature – each species has a two part name – genus & species

• Based on structural and physical similarities of organisms

• He not only named species, he also grouped them into categories.

• Each level if called a taxon

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• Scientists realized there were enough differences among organisms to make 5 kingdoms:

• Monera - bacteria

• Protista

• Fungi

• Plantae

• Animalia

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• Six Kingdoms

• Recently, biologists recognized that Monera were composed of two distinct groups of bacteria

• The six-kingdom system of classification includes:

• Eubacteria

• Archaebacteria

• Protista

• Fungi

• Plantae

• Animalia

Monera

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• The Three-Domain System

• Molecular analyses have given rise to a new taxonomic category that is now recognized by many scientists.

• The domain is more inclusive category than any other-larger than a kingdom.

• The three domains are:

• Eukarya –kingdoms protists, fungi, plants, and animals

• Bacteria

• Archaea

• As new information is gained about organisms in the domains Bacteria and Archaea, they may be subdivided into additional kingdoms.

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• Domain Eubacteria

• unicellular prokaryotes.

• Thick or thin cell walls made of peptidoglycan

• Ex: E. coli, cyanobacteria

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• Domain Archaea

• unicellular prokaryotes.

• live in extreme environments.

• cell walls lack peptidoglycan, and cell membranes contain unusual lipids not found in other organisms.

• Ex: thermophiles, haleophiles

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• Domain Eukarya

• Unicellular and multicellular eukaryotes

• This domain is organized into four kingdoms:

• Protista

• eukaryotic organisms that cannot be classified as animals, plants, or fungi.

• unicellular or multicellular

• photosynthetic or heterotrophic

• Live in moist environments

• Ex: paramecium, kelp, slime mold

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• Fungi

• heterotrophs.

• Most fungi feed on dead or decaying organic matter

• multicellular (mushrooms) or unicellular (yeasts)

• some have cell wall composed of chitin

• do not move from place to place

• Ex: mushrooms, yeast, black mold

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• Plantae

• Multicellular

• photosynthetic autotrophs.

• cannot move from place to place.

• cell walls composed of cellulose.

• includes cone-bearing and flowering plants as well as mosses and ferns

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• Animalia

• multicellular

• heterotrophic.

• do not have cell walls.

• can move about

• complex organ systems

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BIO-QUIZ

18-3

1. Organisms whose cell walls contain peptidoglycan belong in the kingdom a. Fungi.b. Eubacteria.c. Plantae.d. Archaebacteria.

18-3

2. Multicellular organisms with no cell walls or chloroplasts are members of the kingdom a. Animalia.b. Protista.c. Plantae.d. Fungi.

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3. Organisms that have cell walls containing cellulose are found ina. Eubacteria and Plantae.b. Fungi and Plantae.c. Plantae and Protista.d. Plantae only.

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4. Molecular analyses have given rise to a new taxonomic classification that includes a. three domains.b. seven kingdoms.c. two domains.d. five kingdoms.

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5. Which of the following contain more than one kingdom?a. only Archaeab. only Bacteriac. only Eukaryad. both Eukarya and Archaea

• Eight levels of classification are…

• Domain – largest group of classification, a group of related kingdoms

• Kingdom – a group of related phyla

• Phylum – a group of closely related classes

• Class – a group of closely related orders

• Order – a group of closely related families

• Family – a group of closely related genera

• Genus – a group of closely related species

• Species

• most specific level of classification

• a group of organisms that can interbreed and produce fertile offspring

Linnaeus's System of Classification

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BIO-QUIZBIO-QUIZ

18-1

1. Which statement about classification is true?

a. Biologists use regional names for organisms.b. Biologists use a common classification system

based on similarities that have scientific significance.

c. Biologists have identified and named most species found on Earth.

d. Taxonomy uses a combination of common and scientific names to make the system more useful.

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2. Linnaeus's two-word naming system is called

a. binomial nomenclature.b. taxonomy.c. trinomial nomenclature.d. classification.

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3. Several different classes make up a(an) a. family.b. species.c. kingdom.d. phylum.

18-1

4. A group of closely related species is a(an)

a. class.b. genus.c. family.d. order.

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5. Which of the following lists the terms in order from the group with the most species to the group with the least?

a. order, phylum, family, genusb. family, genus, order, phylumc. phylum, class, order, familyd. genus, family, order, phylum

• Did King Phillip Come Over For Great Spaghetti

• Proper way to write a scientific name

• All letters are lower case except the genus is capitalized.

• Genus and species is underlined or italicized

• Ex. eukarya, animalia, chordate, mammalia, primata, hominidae, Homo, sapien

• Dichotomous Key

• A set of paired statements used to help identify organisms

• Read each statement and decide which fits your organism

• Go to where that statement tells you and read the next two statements

• Eventually you will reach a statement that tells you the name of the organism

Choose one of the items from the following list: pine tree, clam, rock, robin, tin can, deer, oak tree, mouse, dandelion, Paramecium, bicycle, ant

1. a. Organism is living....................................go to 4.1.b. Organism is nonliving........ ....................go to 2.

2. a. Object is metallic.....................................go to 3.2. b. Object is nonmetallic................. ..............Rock.

3. a. Object has wheels..............................Bicycle.3. b. Object does not have wheels..............Tin Can.

4. a. Organism is microscopic...........Paramecium.4. b. Organism is macroscopic........................go to 5.

5. a. Organism is a plant.................................go to 6.5. b. Organism is an animal............................go to 8.

6. a. Plant has a woody stem.........................go to 7.6. b. Plant has a herbaceous stem......... .Dandelion.

7. a. Tree has needle like leaves..............Pine Tree.7. b. Tree has broad leaves......................Oak Tree.

8. a. Organism lives on land.........................go to 9.8. b. Organism lives in water...........................Clam.

9. a. Organism has 4 legs or fewer.............go to 10.9. b. Organism has more than 4 legs................Ant.

10 a. Organism has fur................................go to 11.10 b. Organism has feathers.........................Robin.

11 a. Organism has hooves............................Deer.11 b. Organism has no hooves......................Mouse

18.2 Modern Evolutionary Classification

Evolutionary Classification

• Phylogeny – evolutionary relationships among organisms.

• Biologists currently group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.

• The higher the level of the taxon, the further back in time is the common ancestor of all the organisms in the taxon.

• Organisms that appear very similar may not share a recent common ancestor.

• Classification Using Cladograms

• Cladogram – a branching diagram showing the evolutionary relationships among a group of organisms

• Traits that appear in recent parts of a lineage but not in its older members are called derived traits

• Derived traits can be used to construct a cladogram

• Cladograms help scientists understand how one lineage branched from another in the course of evolution

EUBACTERIA ARCHAEBACTERIA EUKARYOTES

Fig. 20.17, p. 327

BIO-QUIZBIO-QUIZ

18-2

1. Grouping organisms together based on their evolutionary history is called

a. evolutionary classification.b. traditional classification.c. cladogram classification.d. taxonomic classification.

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2. Traditional classification groups organisms together based on

a. derived characters.b. similarities in appearance.c. DNA and RNA similarities.d. molecular clocks.

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3. In an evolutionary classification system, the higher the taxon level,

a. the more similar the members of the taxon become.

b. the more common ancestors would be found in recent time.

c. the fewer the number of species in the taxon.

d. the farther back in time the common ancestors would be.

18-24. Classifying organisms using a cladogram

depends on identifyinga. external and internal structural

similarities.b. new characteristics that have appeared

most recently as lineages evolve.c. characteristics that have been present in

the group for the longest time.d. individual variations within the group.

18-2

5. To compare traits of very different organisms, you would use

a. anatomical similarities.b. anatomical differences.c. DNA and RNA.d. proteins and carbohydrates.