Transcript Ajuga reptans - Bibb County Schools

Classification of Life
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Why Classify Organisms?
• To aid them in their study of the
large diversity of organisms,
biologists classify organisms by
naming them and by grouping
them in a logical manner.
• Taxonomy is the discipline
scientists use to classify and
name organisms.
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Binomial Nomenclature
• From the time of Aristotle until the
1700s, all living things were
classified into two kingdoms, the
plant and animal kingdom.
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• In the 1700s, Carolus Linnaeus, a
Swedish botanist, developed a
classification system based on
Carolus Linnaeus
1707 - 1778
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anatomical similarities and
differences.
• Linnaeus developed binomial
nomenclature, a two-word naming
system.
• The first word is the genus. The
genus is always capitalized.
• The second word is the species.
The species is written in
lowercase.
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• Both the genus and the species
are italicized. For example
Homo sapiens (human)
Felix domestica (house cat)
Panthera leo (lion)
Ajuga reptans (ajuga)
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Increasing similarities
• A taxon is a group or level of
organization. Linnaeus used
seven taxons:
Kingdom
Phylum
Class
Order
Family
Genus
Species
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Problem with Linnaean System
• Due to convergent evolution,
organisms that are quite different
from each other evolve similar
body structures.
• These similarities made it hard for
taxonomist to classify many
organisms accurately.
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CONVERGENT EVOLUTION
The process by
which
unrelated
organisms
come to
resemble each
other.
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• Scientist now understand that
organisms share certain traits
because of similarities in their
evolutionary history.
• Biologist now group organisms
into categories based on
evolutionary descent rather than
on physical similarities.
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• This evolutionary classification
uses cladograms to show what
characteristics organisms have in
common.
• Scientists use cladograms to
understand how things are similar
and different.
• See page 452
and handout
provided.
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A Cladogram
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Similarities in DNA and RNA
• The similarities of genes in DNA
and RNA are now used to help
determine classification.
• See handout provided.
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Activity: The Six-Kingdom
Classification System
• The current classification system now
has six kingdoms and three domains.
• Refer to the classification handout
provided.
• Record a brief description of each
domain and each kingdom on the
handout.
• See page 458 in your textbook for
descriptions.
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ACTIVITIES
“Amino Acid Activity”
“Using and Constructing a Classification
Key”
“How to Read a Cladogram”
“Investigating Common Functions Among
Diverse Organisms”
“Introduction to Viruses” – How do viruses fit
into the classification scheme?
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