Classification
Unit 3
Classification Activity
• Please sit down if you:
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Are taller than 5’9”
Have blonde Hair
Have brown Eyes
Are left-Handed
Why Classify?
• To study the diversity of life, biologists use a classification system
to name organisms and group them in a logical manner.
• Taxonomy: science of classification
• By using a scientific name, scientists can be sure everyone is
discussing the same organism.
mountain lion ?
puma?
cougar ?
panther?
Scientific name = Felis concolor
Assigning Scientific Names
• Aristotle attempted to classify organisms based on where they lived
- land, water or air.
• With the invention of the microscope, classifying the diversity of life
became difficult.
• A major step was taken by Carolus Linnaeus who developed
binomial nomenclature (two-name naming system.)
• In binomial nomenclature, each species is assigned a two-part
scientific name, which is always written in italics. First name is
capitalized and second is lowercase.
Binomial Nomenclature
Ursus arctos
Genus
Species
Dichotomous Key
• Tool to help user identify living and non-living things.
• Dichotomous comes from two Greek words that together
mean, “divided into two parts”.
• In each step of the key, only two choices are given; a direction
is given or the organisms scientific name.
Dichotomous Key
Dichotomous Key Activity
Class Activity!
Make your own
Dichotomous Key
Warm-Up!
Linnaeus’s System of
Classification
• Linnaeus's hierarchical system of classification
includes eight levels:
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Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
• Each level is called a taxon (pl. taxa).
• Species: organisms that look alike and inter-breed under
natural conditions.
Trick!
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Definitely
Keep
Pond
Clean
Or
Froggy
Gets
Sick
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Read and Respond
Warm-Up!
• What are the eight levels of classification?
• What are the 3 domains?
• What are the 6 kingdoms?
Kingdoms and Domains
• Linnaeus's two kingdoms, Animalia and Plantae did not adequately
represent the diversity of life.
• Microorganisms became kingdom Protista.
• Mushrooms, yeasts and molds were placed in Fungi.
• Later, bacteria were named kingdom Monera.
• More recently, kingdom Monera was subdivided into two groups:
Eubacteria and Archaebacteria.
Domains
• Three domains
• Eukarya (Protists, Fungi, Plantae, Animalia)
• Bacteria (Eubacteria)
• Archaea (Archaebacteria)
Domain Bacteria
Domain Bacteria
• Extremely Diverse
• Some photosynthetic
• Some pathogenic (causing disease)
• Some need oxygen to live, others are killed by oxygen
Streptococcus
Escherichia coli
Domain Archaea
Domain Archaea
• Live in extreme environments
• Volcanic hot springs
• Brine pools
• Bottom of the ocean
• Many can only survive in the absence of oxygen
Halophiles
Methanogens
Domain Eukarya
Eukarya-Protista
• Great variety
• Three basic groups
• Animal-like
• Plant-like
• Fungi-like
Amoeba
Paramecium
Eukarya-Fungi
• Feed on dead or decaying matter
• Secrete digestive enzymes, then absorb small molecules
• Cell walls made of chitin
Eukarya-Plantae
• Non motile-cannot move from place to place
• Cell walls made of cellulose
Eukarya-Animalia
• Heterotrophic – must eat others to survive
• No cell walls
Time to Practice!
• Pg 461: # 3-5
• Pg 463: Classify the leaves using dichotomous key
• Pg 465: #1-5, 8-10