Download chapter-1-evaluate-lesson-2-classifying-organisms

Middle School Science
Room 212 – Miss Lida
Chapter 1/Evaluate (Lesson 2)
“Classifying Organisms”
Classifying Living Things
 Greek philosopher, Aristotle (384 B.C. – 322 B.C.), was one of the first
people to classify organisms. He classified animals based on the presence of
“red blood”, an animal’s environment, shape, and size.
 He classified plants according to the structure and size of the plant and
whether it was a tree, shrub, or herb.
Determining Kingdoms
 In the 1700’s, Carolus Linnaeus, a Swedish physician and botanist, placed all
organisms into two main groups called kingdoms.
 In 1968, American biologist, Robert H. Whittaker, proposed a five-kingdom
system for classifying organisms. His system included kingdoms: Monera,
Protista, Plantae, Fungi, and Animalia.
Determining Domains
 Current classification system is called “systematics”.
 Uses all evidence known about organisms to classify them (cell type,
habitat, how it obtains food and energy, structure and function of features,
and common ancestry of organisms.
 Also includes molecular analysis (the study of molecules such as DNA within
organisms).
*Using systematics, scientists identified 2 distinct groups in Kingdom Monera:
Bacteria and Archaea. This led to the development of another level of
classification called “domains”.
All organisms are now classified into one of 3 domains --- Bacteria, Archaea, or
Eukarya, and then into one of 6 kingdoms.
 Bacteria
 Archaea
 Protista
 Fungi
 Plantae
 Animalia
Scientific Names
 Linnaeas also developed a system for naming organisms. System called
binomial nomenclature.
Bionomial Nomenclature
 Gives each organism a two-word scientific name. The scientific name is the
name of an organism’s species.
Species – is a group of organisms that have similar traits and are able to
produce fertile offspring.
Genus – is a group of similar species
* Similar species are grouped into one genus. (plural: genera)
Similar genera are grouped into families, orders, classes, phyla, kingdoms,
and domains.
Uses of Scientific Names
 Each species has its own scientific name
 Scientific names are the same worldwide
Dichotomous Keys
 A dichotomous key is a series of descriptions arranged in pairs that
leads the user to the identification of an unknown organism.
 Choices continue until the organism is identified.
Cladograms
 A cladogram is a branched diagram that shows the relationship among
organisms, including common ancestors.