pearland high school 2008 chapter 18 thediversity of life
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Pearland High School 2008
Chapter 18
TheTheDiversityDiversityof Lifeof Life
Tacitus
bellus
Populus tremuloides
Quaking Aspen
Finding Order in Diversity• To study the diversity of life,
biologists use a classification system to name organisms and group them in a logical manner.
• Taxonomy is the branch of biology that groups and names organisms based on studies of their different characteristics.
• Biologists who study taxonomy are called taxonomists.
• Classification systems change with expanding knowledge.
Carolus von Linnaeus(1707-1778)
Carolus Linnaeus• Swedish botanist• Developed Binomial
Nomenclature• Two-word naming system
– Genus» Noun, Capitalized,
Underlined or Italicized
– Species» Descriptive, Lower Case,
Underlined or Italicized
– Each species is assigned a two-part scientific name
» Ex. Ursus arctos
System of Classification
• Linnaeus’s hierarchical system of classification includes seven levels (from largest to smallest)
• Grizzly Bear (common name)– Kingdom Animalia
– Phylum Chordata
– Class Mammalia
– Order Carnivora
– Family Ursidae
– Genus Ursus
– Species arctos
Each of the levels is called a TAXONUrsus
arctos(scientific name)
System of Classification
• Taxonomic categories, an acronym:– Kingdom King– Phylum Phillip– Class Came– Order Over– Family For– Genus Good– Species Soup
KKPPCCOOFFGGSS
• Phylogeny – evolutionary relationships among organisms
• Evolutionary classification – strategy of grouping organisms together based on their evolutionary history– Fossil record– Comparative homologies– Comparative sequencing of
DNA/RNA among organisms– Molecular clocks
Evolutionary Classification
Represent hypothesized evolutionary relationships
Taxonomic Diagrams
PhylogeneticTree
Mammals Turtles Lizards and Snakes Crocodiles Birds
Attempt to trace the process of evolution by
focusing on shared features
Mammals Turtles Lizards and Snakes Crocodiles Birds
CladogramTaxonomic Diagrams
Dichotomous Keys Identify Organisms
• Dichotomous keys contain pairs of contrasting descriptions.
• After each description, the key directs the user to another pair of descriptions or identifies the organism.
Example: 1. a) Is the leaf simple? Go to 2
b) Is the leaf compound? Go to 3
2. a) Are margins of the leaf jagged? Go to 4
b) Are margins of the leaf smooth? Go to 5
Domains• Most inclusive category • Larger than a kingdom• There are 3
– Eukarya – includes the kingdoms»Protists, Fungi, Plants &
Animals– Bacteria – corresponds to the
kingdom Eubacteria– Archaea – corresponds to the
kingdom Archaebacteria
Kingdoms• Monera (Eubacteria and
Archaebacteria) - Prokaryotes, with or without peptidoglycan in cell walls
• Protista – Eukaryotes, diverse, not fungi, plants, or animals
• Fungi – Eukaryotes, multicellular (except yeasts), heterotrophic, chitin in cell walls
• Plantae – Eukaryotes, multicellular, autotrophic, cell wall containing cellulose
• Animalia – Eukaryotes, multicellular, heterotrophic, no cell wall
Kingdom Monera - Eubacteria• Common name: Bacteria• Unicellular prokaryotes• Peptidogylcan in cell wall• Ecologically diverse • Basic shapes are cocci,
bacilli, spirilla• Reproduce both sexually and
asexuallyBacillus anthracis(spores can live in
soil for years)
Streptococcus mutans
(can cause endocarditis and
dental caries)
Kingdom Monera - Archaebacteria• Cell wall does not contain
peptidogylcan• Cell membrane contains unusual
lipids not found in other organisms• Live in extreme environments
(devoid of oxygen):– volcanic hot springs– brine pools– black organic mud
Archaeafirst detected in
extreme environments,
such as volcanic hot springs.
Kingdom Protista• A classification problem – consists
of organisms that cannot be classified as animals, plants, or fungi
• Most unicellular, some colonial and some multicellular
• Autotrophic and heterotrophic• Some move with flagella,
pseudopods or cilia• Animal-like, plant-like and fungus-
like groups• Reproduce by mitosis and meiosis
Entamoeba histolytica
Kingdom Fungi
• Most feed on dead of decaying organic matter by secreting digestive enzymes into their food source then absorbing it into their bodies
• Cell walls of chitin• Most multicellular; some
unicellular• Heterotrophic
Boletus zelleri(Edible, but often infected with fly
larvae)
Epidermophyton floccosum
(one of the causes of
athlete's foot)
Kingdom Plantae
• Multicellular• Nonmotile – cannot
move from place to place
• Cell wall with cellulose• Mostly photosynthetic
autotrophs
Sunflowers in Fargo, North
Dakota
Ginkgo bilobaGinkgos are often very long-lived.
Some specimens are thought to be more than 3,500
years old.
Kingdom Animalia
• Multicellular• Heterotrophic• No cell walls or
chloroplasts• Incredible diversity
Chambered
Nautilus
Colony of sponges
Hymenoptera Dialictus zephrum
Txodes scapularisDeer tick
Hierarchical Systemof Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
SpeciesFrom
general to more specific
How Many Kingdoms?
6Kingdoms
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