Page 56 - Science Course 1 (Book 1)

Mo2-L3a: How are Organisms Classified?

Let’s Begin Determining Domains

Classifying Living Things The current classification method for organisms is
called systematics.
There have been many
different ideas about how
to organize, or classify,
living things.

Carolus Linnaeus
classified organisms
into two main groups, Bacteria Eukaryota
called kingdoms,
based on similar
structures.

Archaea
Systematics uses all known evidence to classify
organisms, including cell type, how food and ener-
gy are obtained, structure and function of features,
common ancestry, and molecular analysis.

Key Concept

What evidence is used to classify living things into groups?

Organisms are now classified into one of three domains and then into one of six kingdoms.

DOMAINS AND KINGDOMS

DOMAIN BACTERIA ARCHAEA EUKARYA

Kingdom Bacteria Archaea Protista Fungi Plantae Animalia
Example

Characteristics Bacteria Archaea Protists are Fungi are Plants are Animals are
are simple are simple unicellular unicellular or multicellular multicellular
unicellular unicellular and are more multicellular and make and take in
organisms. organisms complex than and absorb their own their food.
that often live bacteria or food.
in extreme archaea
enviroments.

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