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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Section:
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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Section:
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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Section:
Flowchart
Section 18-1
Linnaeus’s System of Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
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Section:
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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Section:
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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Section:
Section Outline
Section 18-2
18–2
Modern Evolutionary Classification
A.
B.
C.
D.
E.
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Section:
Which Similarities Are Most Important?
Evolutionary Classification
Classification Using Cladograms
Similarities in DNA and RNA
Molecular Clocks
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
CLASSIFICATION
BASED ON VISIBLE
SIMILARITIES
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Section:
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
CLASSIFICATION
BASED ON VISIBLE
SIMILARITIES
Go to
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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Section:
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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Section:
Section Outline
Section 18-3
18–3
Kingdoms and Domains
A.
B.
C.
D.
E.
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Section:
The Tree of Life Evolves
The Three-Domain System
Domain Bacteria
Domain Archaea
Domain Eukarya
1. Protista
2. Fungi
3. Plantae
4. Animalia
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
Go to
Section:
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
Eukarya
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
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Section:
Figure 18-13 Cladogram of Six Kingdoms
and Three Domains
Section 18-3
DOMAIN
ARCHAEA
DOMAIN
EUKARYA
Kingdoms
DOMAIN
BACTERIA
Go to
Section:
Eubacteria
Archaebacteria
Protista
Plantae
Fungi
Animalia
Videos
Click a hyperlink to choose a video.
Panthera leo?, Part 1
Panthera leo?, Part 2
Video 1
Panthera leo?, Part 1
Click the image to play the video segment.
Video 2
Panthera leo?, Part 2
Click the image to play the video segment.
Go Online
Links from the authors on the search for new species
Interactive test
For links on classification, go to www.SciLinks.org and enter the Web
Code as follows: cbn-5181.
For links on domains of life, go to www.SciLinks.org and enter the Web
Code as follows: cbn-5183.
Interest Grabber Answers
1. Consider the task facing early biologists who attempted to organize living
things. How might they have begun?
Students may say that early biologists attempted to formulate logical
systems for organizing the diversity of life.
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?
Students may group the plantlike, sessile organisms (the plant, seaweed,
and mushroom) together, grouping the others as animals.
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.
Remind students that organizational systems are human-made, and there
are no right or wrong ones. Some, however, are more useful
than others.
Interest Grabber Answers
1. Do you think roses and orchids are closely related? Explain your answer.
Students may say that their different growth habits and inability to hybridize
indicate that they are not closely related.
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?
Students may know that all domestic dogs are a single species.
3. What defines a species? Is appearance important? What other factors
might be considered?
Students may suggest that a species is defined by its members’ ability to
interbreed, regardless of appearance.
Interest Grabber Answers
1. What categories could you use to organize your count of vehicles?
Students’ answers may include, type of vehicle, color, age, or
manufacturer.
2. Look at your list of categories. Are all of them equally useful?
Students may suggest that the usefulness of the criteria depends on the
intent of the study.
3. Is there more than one valid and useful way to organize living things?
Students should conclude that the same set of living things could be
categorized in several ways, depending upon the criteria used.
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