Download Section 18-1

Interest Grabber
Section
18-1
Order From Chaos
When you need a new pair of shoes, what do you do?
You probably walk confidently into a shoe store, past
the tens or hundreds of pairs of shoes you don’t want
and straight to the kind you do want. How do you find
them? Shoes are organized in the store in categories.
People organize objects by grouping similar objects
together.
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Interest Grabber continued
Section 18-1
1. Consider the task facing early biologists who attempted to
organize living things. How might they have begun?
2. Suppose that you have been given a green plant, stringy brown
seaweed, a rabbit, a mushroom, a worm, and a grasshopper.
You’ve been asked to organize these things into categories that
make sense. How would you do it?
3. Decide on your categories and write each on a sheet of paper.
Next to each category, write the defining characteristics of that
category. Then, write in the organisms that fall into each
category.
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Answers
Order From Chaos
1. Students may say that early biologists attempted to
formulate logical systems for organizing the diversity of
life.
2. Students may group the plantlike, sessile organisms (the
plant, seaweed, and mushroom) together, grouping the
others as animals.
3. Remind students that organizational systems are
human-made, and there are no right or wrong ones.
Some, however, are more useful than others.
Section Outline
Section 18-1
18–1 Finding Order in Diversity
A. Why Classify?
B. Assigning Scientific Names
1. Early Efforts at Naming
Organisms
2. Binomial Nomenclature
C. Linnaeus’s System of
Classification
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Words to Know
Taxonomy – classifying organisms and assigning each
organism a universally accepted name
Carolus Linnaeus – Swedish botanist who developed a
two-word naming system called binomial nomenclature
The scientific name:
•The first word is the genus and it is capitalized
•The second word is the species and it is lowercased
•It is always written in italics
Examples
Felis concolor – mountain lion, puma, cougar, panther
Ursus arctos (grizzly bear) and Ursus maritimus (polar
bear) belong to the same genus, but not the same
species
Taxonomic Categories (Taxa) {Singular: taxon}
•Kingdom, Phylum, Class, Order, Family, Genus,
Species (Larger category to more specific)
•Genera that share many characteristics are grouped in
a larger category, the family
•An order is a broad taxon composed of similar families
•A class is composed of similar orders
•Several different classes make up a phylum
Flowchart
Section 18-1
Linnaeus’s System of Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
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Figure 18-5 Classification of Ursus arctos
Section 18-1
Grizzly bear Black bear
Giant
panda
Red fox
Coral Sea star
Abert
squirrel snake
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
ORDER Carnivora
FAMILY Ursidae
GENUS Ursus
SPECIES Ursus arctos
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Interest Grabber
Section 18-2
One Big Family?
How can you determine if one organism is closely
related to another? It may seem easy, but it isn’t, and
looks are often deceiving. For example, roses and
orchids are both flowering plants, but roses grow on
bushes or vines and have thorns. Many orchids don’t
even grow in soil—they can grow in trees! Rose and
orchid blossoms look very different, and roses and
orchids cannot produce hybrids, or offspring of crosses
between parents with different traits.
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Section:
Interest Grabber continued
Section 18-2
1. Do you think roses and orchids are closely related?
Explain your answer.
2. Now, apply the same logic to dogs. Different breeds
of dogs—such as a Labrador retriever and a collie—
can breed and produce offspring. So what is the
difference between the rose-orchid combination and
the Lab-collie combination?
3. What defines a species? Is appearance important?
What other factors might be considered?
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Answers
One Big Family?
1. Students may say that their different growth habits
and inability to hybridize indicate that they are not
closely related.
2. Students may know that all domestic dogs are a
single species.
3. Students may suggest that a species is defined by its
members’ ability to interbreed, regardless of
appearance.
Section Outline
Section 18-2
18–2 Modern Evolutionary Classification
A.Problems With Traditional
Classification
B.Evolutionary Classification
C.Classification Using Cladograms
D.Similarities in DNA and RNA
E.Molecular Clocks
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Words to Know
Traditional classification – organisms were grouped
according to similarities in appearance
Evolutionary classification – grouping organisms based
on their evolutionary history
Cladistic analysis – identifies and considers only those
characteristics of organisms that are evolutionary
innovations (new characteristics that arise as lineages
evolve over time)
Derived characters – characteristics that appear in
recent parts of a lineage but not in its older members
Cladogram – a diagram that shows the evolutionary
relationships among a group of organisms (derived
characters such as free-swimming larva and
segmentation)
The genes of many organisms show important
similarities at the molecular level. (American vultures
are more closely related to storks than to African
vultures. A gene that codes for myosin protein indicates
that humans and yeast have a common ancestry.)
Molecular clock – uses DNA comparisons to estimate
the length of time that two species have been evolving
independently (Longer=more different)
Traditional Classification Versus Cladogram
Section 18-2
Appendages
Crab
Conical Shells
Barnacle
Limpet
Crustaceans
Crab
Gastropod
Barnacle
Limpet
Molted
exoskeleton
Segmentation
Tiny free-swimming larva
TRADITIONAL
CLASSIFICATION
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CLADOGRAM
Traditional Classification Versus Cladogram
Section 18-2
Appendages
Crab
Conical Shells
Barnacle
Limpet
Crustaceans
Crab
Gastropod
Barnacle
Limpet
Molted
exoskeleton
Segmentation
Tiny free-swimming larva
TRADITIONAL
CLASSIFICATION
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Section:
CLADOGRAM
Interest Grabber
Section 18-3
My Way or the Highway
Categories that are used to organize an assortment of
things should be valid. That is, they should be based on
real information. However, categories should be useful,
too. Suppose that you are taking a survey of traffic. You
sit at the side of a busy intersection and record the
vehicles you see in one hour.
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Interest Grabber continued
Section 18-3
1.What categories could you use to organize your count
of vehicles?
2. Look at your list of categories. Are all of them equally
useful?
3. Is there more than one valid and useful way to
organize living things?
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Interest Grabber
My Way or the Highway
1. Students’ answers may include, type of vehicle, color,
age, or manufacturer.
2. Students may suggest that the usefulness of the criteria
depends on the intent of the study.
3. Students should conclude that the same set of living
things could be categorized in several ways, depending
upon the criteria used.
Section Outline
Section 18-3
18–3 Kingdoms and Domains
A.The Tree of Life Evolves
B.The Three-Domain System
C .Domain Bacteria
D .Domain Archaea
E .Domain Eukarya
1. Protista
2. Fungi
3. Plantae
4. Animalia
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Two Kingdoms – animals and plants (1700s)
Three Kingdoms – animals, plants, and protists
(microorganisms) [Late 1800s]
Four Kingdoms – animals, plants, protists, fungi
(mushrooms, yeasts, molds)
Five Kingdoms – monera, protista, fungi, plantae, and
animalia (1950s)
Six Kingdoms – Eubacteria, Archaebacteria, Protista,
Fungi, Plantae, Animalia
Three Domains – Bacteria, Archaea (live in extreme
environments), Eukarya
Concept Map
Section 18-3
Living
Things
are characterized by
Eukaryotic
cells
and differing
Important
characteristics
which place them in
Cell wall
structures
such as
Domain
Eukarya
Prokaryotic cells
which is subdivided into
which place them in
Domain
Bacteria
Domain
Archaea
which coincides with
which coincides with
Kingdom
Eubacteria
Kingdom
Archaebacteria
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Kingdom
Plantae
Kingdom
Fungi
Kingdom
Protista
Kingdom
Animalia
Figure 18-12 Key Characteristics of
Kingdoms and Domains
Section 18-3
Classification of Living Things
DOMAIN
Bacteria
Archaea
KINGDOM
Eubacteria
Archaebacteria
CELL TYPE
Protista
Fungi
Plantae
Animalia
Prokaryote
Prokaryote
Eukaryote
Eukaryote
Eukaryote
Eukaryote
Cell walls with
peptidoglycan
Cell walls
without
peptidoglycan
Cell walls of
cellulose in
some; some
have
chloroplasts
Cell walls of
chitin
Cell walls of
cellulose;
chloroplasts
No cell walls
or chloroplasts
Unicellular
Unicellular
Most unicellular;
some colonial;
some
multicellular
Most
multicellular;
some
unicellular
Multicellular
Multicellular
MODE OF
NUTRITION
Autotroph or
heterotroph
Autotroph or
heterotroph
Autotroph or
heterotroph
Heterotroph
Autotroph
Heterotroph
EXAMPLES
Streptococcus,
Escherichia coli
Methanogens,
halophiles
Amoeba,
Paramecium,
slime molds,
giant kelp
Mushrooms,
yeasts
Mosses, ferns,
flowering
plants
Sponges,
worms,
insects, fishes,
mammals
CELL
STRUCTURES
NUMBER OF
CELLS
Monera - Eubacteria and Archaebacteria
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Eukarya
Methanogens: produce methane as a byproduct
Halophiles: “salt loving”
Figure 18-13 Cladogram of Six
Kingdoms and Three Domains
Section 18-3
DOMAIN
ARCHAEA
DOMAIN
EUKARYA
Kingdoms
DOMAIN
BACTERIA
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Eubacteria
Archaebacteria
Protista
Plantae
Fungi
Animalia