U6 L3 Classification of Living Things

Unit 6 Lesson 3 Classification of Living Things

Copyright © Houghton Mifflin Harcourt Publishing Company


Indiana Standards


• 8.3.6 Observe anatomical structures of a variety of organisms and describe their similarities and differences. Use the data collected to organize the organisms into groups and predict their relatedness.

Sorting Things Out!


Why do we classify living things?

• Scientists classify living things based on characteristics that living things share.

• Classification helps scientists to answer questions about organisms.

• Classification helps a scientist keep living things organized.


How do scientists know living things are related?• Physical characteristics can indicate that two

organisms are similar or related.

• Scientists also study how organisms develop from an egg to an adult to determine if organisms are related.



How do scientists know living things are related?• Chemical characteristics can indicate whether

organisms are similar or related.

• Scientists use genetic material to look for mutations and genetic similarities.

• Proteins and hormones also can show if organisms are related.



What’s in a Name?


How are living things named?

• Carolus Linnaeus simplified classification with a two-part scientific name.

• A species is a group of organisms that are very closely related.

• Members of the same species can mate and produce fertile offspring.


How are living things named?

• A genus includes similar species.

• The genus is the first part of a scientific name. The genus name is always CAPITALIZED. The species name follows and is lowercase.

• All organisms have a unique two-part scientific name that is italicized or underlined.



What are the levels of classification?

• Taxonomy is the science of describing, classifying, and naming living things.

• Scientists use an eight-level classification system.

• Each level is more specific than the one before it and contains a smaller group of living things.



What are the levels of classification?



Triple Play


What are the three domains?

• Scientists used to use a six-kingdom classification system, but later added the domain.

• A domain represents the largest differences among organisms in classification.

• The three domains are Bacteria, Archaea, and Eukarya.



• Domain Bacteria is made up of prokaryotes that typically have a cell wall and reproduce by cell division.

• Domain Archaea is made up of prokaryotes that differ from bacteria in their genetics and in the makeup of their cell walls.




• Domain Eukarya is made up of all eukaryotes.

• Eukaryotes have cells with a nucleus and membrane-bound organelles.

• Plants, animals, protists, and fungi in the Domain Eukarya can be single-celled or multicellular.



My Kingdom for a Eukaryote!


What kingdoms are in Eukarya?

• Kingdom Animalia contains multicellular organisms that lack cell walls, are typically able to move around, and have specialized sense organs.

• Kingdom Plantae consists of multicellular organisms that have cell walls, cannot move around, and make their own food.


What kingdoms are in Eukarya?

• Kingdom Protista are single-celled or simple multicellular organisms such as algae, protozoans, and slime molds.

• Kingdom Fungi are single-celled or multicellular organisms that get energy by absorbing materials and have cells with cell walls but no chloroplasts.



How do classification systems change?

• Millions of organisms are not named.

• New organisms do not always fit into the existing classification system.

• Scientists are constantly changing their thoughts on classification based on new information.



How are classification relationships illustrated?• Branching diagrams are often used in

classification.

• A cladogram is a branching diagram that shows relationships among species.



How are classification relationships illustrated?• Organisms to the right have a particular

characteristic. Organisms on branches to the left do not.



Keys to Success


How can organisms be identified?

• A dichotomous key uses a series of paired statements to identify organisms.

• The pairs of statements are numbered.

• Once you choose a correct statement from a pair, you are directed to a new pair of statements until the organism is identified.


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U6 L3 Classification of Living Things

Science