Why do Scientists Classify? Imagine a grocery store How are
they organized? What would happen if they were not organized? How
is your life organized?
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Why do Scientists Classify? Almost 13 billion known species of
organisms Need to keep organized! (Easier to study!) Classification
the grouping of information or objects based on similarities.
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Why do Scientists Classify? Taxonomy is the science of grouping
and naming organisms. Useful because: once classified, scientists
will know a lot about an organism
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Early Classification Systems Aristotle (4 th century B.C.)
-observed animals -watched appearance, behavior, movement -fly,
swim, and walk/crawl/run -observed similarities and differences
-used differences to divide into smaller subgroups
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Linnaeus Carolus Linnaeus (1750s) -used observations as basis
of his system -placed organisms based on observable features
Devised naming system for organisms: Binomial Nomenclature
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Linnaeus Binomial Nomenclature- 2 part naming system -uses
Latin words First name (genus); second name (species) Genus
speciesFelis concolor Genus is capitalized; species is NOT. If you
cant italicize, underline the genus and species!
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Classification Today Species with similar evolutionary
histories are classified more closely together. -when organisms
share a common ancestor, they share an evolutionary history
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Levels of Classification -based on contributions of both
Aristotle and Linnaeus There are 7 levels of classification.
Remember the first letter of this sentence: King Philip Came Over
For Good Spaghetti.
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7 Levels of Classification Kingdom broadest level Phylum Class
Order Family Genus Speciesmost specific
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Levels of Classification
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Taxonomic Categories Taxon- a named group of organisms Taxa
range from having broad diagnostic characteristic to having
specific characteristics Genus- is defined as a group of species
that are closely related and share a common ancestor
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Taxonomic Categories Family- is the next higher taxon,
consisting of similar, related genera. Ursidae family contains 9
species of bears
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Higher Taxa Order- contains related families Class- contains
related orders Bears belong to order carnivora and class
mammalia
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Higher Taxa Phylum or division- contains related classes
Kingdom- contains related phlya or divisions Domain is the broadest
of all taxa and contains one or more kingdoms Bears are classified
in phylum chordata, Kingom Animalia, and Domain Eukarya
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Using the Classification System Field guides help identify
organisms. -they highlight differences between similar organisms
(like trees) Taxonomic Key (AKA Dichotomous Key) -paired statements
that describe the physical characteristics of different
organisms
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Taxonomic Key 1. Fruits occur
singly....................................................... Go to
3 1' Fruits occur in clusters of two or
more......................... Go to 2 2. Fruits are
round....................................................... Grapes
2' Fruits are
elongate................................................... Bananas
3. Thick skin that separates easily from flesh.............Oranges
3' Thin skin that adheres to flesh.............................. Go
to 4 4. More than one seed per fruit............................
Apples 4' One seed per
fruit............................................ Go to 5 5. Skin
covered with velvety hairs.................... Peaches 5' Skin
smooth, without hairs........................... Plums
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19 Broadest, most inclusive taxonBroadest, most inclusive taxon
Three domainsThree domains Archaea and Eubacteria are unicellular
prokaryotes (no nucleus or membrane-bound organelles)Archaea and
Eubacteria are unicellular prokaryotes (no nucleus or
membrane-bound organelles) Eukarya are more complex and have a
nucleus and membrane- bound organellesEukarya are more complex and
have a nucleus and membrane- bound organelles Domains
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20 Archaea live in harsh environments and may represent the
first cells to have evolved. Sewage treatment plants, thermal
vents, etc.
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21 Eubacteria, some of which cause human diseases, are present
in almost all habitats on earth. Many bacteria are important
environmentally and commercially. Live in the intestines of
animals
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22 Domain Eukarya is Divided into Kingdoms Protista
(protozoans, algae)Protista (protozoans, algae) Fungi (mushrooms,
yeasts )Fungi (mushrooms, yeasts ) Plantae (multicellular
plants)Plantae (multicellular plants) Animalia (multicellular
animals)Animalia (multicellular animals)
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23 Protista Most are unicellularMost are unicellular Some are
multicellularSome are multicellular Some are autotrophic, while
others are heterotrophicSome are autotrophic, while others are
heterotrophic
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24 Fungi Multicellular, except yeastMulticellular, except yeast
Absorptive heterotrophs (digest food outside their body & then
absorb it)Absorptive heterotrophs (digest food outside their body
& then absorb it) Cell walls made of chitinCell walls made of
chitin
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25 Plantae MulticellularMulticellular AutotrophicAutotrophic
Absorb sunlight to make glucose PhotosynthesisAbsorb sunlight to
make glucose Photosynthesis Cell walls made of celluloseCell walls
made of cellulose
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26 Animalia MulticellularMulticellular Ingestive heterotrophs
(consume food & digest it inside their bodies)Ingestive
heterotrophs (consume food & digest it inside their bodies)
Feed on plants or animalsFeed on plants or animals
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Similarities and Differences in the Protist Kingdom All are
eukaryotes (cells with nuclei). Live in moist surroundings.
Unicellular or multicellular. Autotrophs, heterotrophs, or both.
Some can move - others cannot.
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3 categories of Protists: Animal-like Fungus-like
Plant-like
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Animal-like Protists (Protozoans) * Unicellular Heterotrophs
*Four groups based on movement: those with flagella, cilia,
pseudopods, and the others.
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Protozoans with Pseudopods Pseudopods also called false feet
Cell membrane pushes in one direction & the cytoplasm flows
into the bulge. This allows the protozoan to move, dragging the
rest of the cell behind it.
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Pseudopod Movement EXAMPLE OF HOW PSEUDOPODS MOVE PUSH FLOW
DRAG
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They can form pseudopods to surround & trap food. Then form
a food vacuole to break down food in the cytoplasm. Pseudopods
& Feeding
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Reproduce by mitosis Contractile vacuole - it collects extra
H2O & expels it from cell Thin cell membrane No definite shape.
Example - Amoeba Pseudopods
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Protozoans with cilia Cilia - hairlike structures - help
organisms move, get food and sense environment. Multicellular with
2 nuclei. 1 nuclei controls everyday functions 1 nuclei is for
reproduction. Reproduce by mitosis or conjugation.
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Ciliates Oral groove lined with cilia - moves H20 containing
food into food vacuole at end of oral groove. Food vacuole breaks
down food and sends through cell. Anal pore sends out waste.
Example of protozoan w/ cilia: paramecium.
Protozoans with flagella Organisms called zooflagellates Use
long whiplike part called flagella to move. These usually live
inside other organisms.
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Other Protozoans Called sporozoans - parasites Feed on cells
& body fluids of hosts Sporozoans like Plasmodium (causes
malaria) have more than 1 host: mosquitoes and then humans
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Examples of Animal-like Protista Cilates- move by cilia
Sarcodines- pseudopods Sporozoans- spores Zooflagellate-
Flagella
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Plantlike Protists Better known as algae Autotrophs Size:
unicellular to very large Contain different pigments so they come
in different colors. Euglena: special type of algae -when there is
no sunlight they become heterotrophic.
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Plant-like protists are algae. Algae are eukaryotic autotrophs.
They, along with other eukaryotic autotrophs, form the foundation
of Earths food chains. They produce much of Earths oxygen.
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There are three unicellular phyla of algae: Phylum Euglenophyta
Phylum Bacillariophyta Phylum Dinoflagellata
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Members of first phylum of algae, Euglenophyta, are both
plant-like and animal-like. Euglena are autotrophs since they make
food from sunlight and Heterotrophs since they ingest food from
surrounding water.
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The second unicellular algae, Bacillariophyta, are
photosynthetic autotrophs. They have shells of silica. They make up
a large portion of the worlds phytoplankton which is Earths largest
provider of oxygen.
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DIATOMS
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The third unicellular algae, Dinoflagellata, are a major
component of marine phytoplankton. These algae have at least two
flagella set at right angles to each other and thick cell walls
made of cellulose plates. Blooms of dinoflagellates cause Red
Tide.
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Multicellular algae are classified by color.
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Rhodophyta are red seaweeds. They are found in warm or cold
marine environments along coast lines in deeper water. They absorb
green, violet, and blue light waves. These light waves are able to
penetrate below 100 meters.
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Phylum Phaeophyta is made up of the brown algae. They are found
in cool saltwater along rocky coasts. Giant Kelp are the largest
and most complex brown algae. They have hold fasts and air
bladders.
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The last of the multicellular algae are the green algae from
the Phylum chlorophyta. Most green algae are found in fresh water
habitats.
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A Volvox is a hollow boll composed of hundreds of flagellated
cells in a single layer.
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Chlamydomonas are actually unicellular and flagellated.
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Funguslike Protists Like animals, they are heterotrophs Like
plants, they have cell walls Reproduce by spores (tiny cells that
can grow into a new organism) Not in fungi kingdom because they can
move at one point in their lives. Example are water or slime
molds.
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Fungus-like protists, Myxomycota and Oomycota are decomposers.
Phylum Myxomycota are made up of plasmodial slime molds. Phylum
Oomycota is made up of water molds and downy molds.