The Linnaean Classification System
The Modern Classification System

Engage

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Driving Question:

What are the Levels of Classification?

In addition to naming organisms, scientists also try to organize, or classify, living species into larger groups that have biological meaning. In a classification system, organisms in a particular group are more similiar to one another than they are to organisms in other groups. Click on the link below to try your skills on the classification game.

 

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Did You Know

Whether you realize it or not, you use classification systems all the time. You may, for example talk about "teachers" or "doctors." Sometimes you refer to a smaller, more specific group, such as " science teacher" or "pediatrician."

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When you do this you refer to these groups using widely accepted names and characteristics that many people understand.

Watch for the following terms and keep a list of their definitions in your notebook as you read through this lesson:

 Attribution:

Images from paid subscription

Classification Hangman in Public Domain

 

 

 

Explore

In the upcoming section you will be learning the Linnaean Classification System. Try the following interactive activity and place the levels in order from broadest to most specific level. Don't worry if you miss it a few times just remember to come back later after you have completed this lesson and try again.

 

  

  

 

  

 

 

 

Explain

Two common methods of classification are the Linnaean and the phylogenetic systems. In the beginning, the Linnaean classification system, which organizes organisms into seven taxa (singular: taxon), tended to reflect physical similarities. Phylogenetic classification concerns itself with such evolutionary relationships, visually expressing those relationships in phylogenetic trees and cladograms. Both methods will be discussed below.

 

The Linnaean Classification System

Carolus Linnaeus, an 18th century botanist, developed the first classification system.   In the Linnaean classification system, all organisms are placed in a ranked hierarchy.   His system was one of small groups building into larger ones. The current groupings of organisms from largest to smallest are: kingdom, phylum, class, order, family, genus, species. Within these groups, the higher you go, the less similar organisms in the group may appear. Few organisms, however, may share some similar characteristics. Alternately, as you move downward, the organisms become more and more similar. There are 3 domains of life:  Bacteria, Archaea, and Eukarya. These domains encompass the six kingdoms.

For those new to this system, it can be a challenge simply remembering these categories. Here's a mnemonic referring to 16th-century Spanish exploration that might help:

King Philip Crossed Over For Gold and Silver

 

 

 Here is a diagram showing the levels. Once again, the main categories that biologists use are listed here from the broadest level to the most specific.

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 Toggle open/close quiz question

 

  

 

 

Binomial Nomenclature

Linnaeus also developed a two-word naming system called binomial nomenclature. In the binomial nomenclature system, each species is assigned a two-part scientific name. The scientific name is always written in italics. The first word is a 'generic name,' which is called the genus (pl. genera) and is always capitalized.   The second word is the 'specific name,' the species and is written lowercase. It might tell you something about the organism-what it looks like, where it is found, or who discovered it.

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Both the genus and species names are written in Latin because that was the language used by scientists during Linnaeus's time.

A complete scientific name is written in Italicsor underlined.

For example: Canis latrans

The genus is capitalized - Canis

The species is in lower case - latran

This is true ALL THE TIME !!!!

So don't forget.

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Having a universal system of binomial nomenclature allows scientists to, in essence, speak the same language when referring to living things, and avoids the confusion of multiple common names that may differ based on region, culture or native language. Look at the table below can you complete the genus and species for humans? Write your answer in your science notes and check your answer below by clicking on the image.

 

Common Name

Genus

Species

dog

Canis

familiaris

wolf

Canis

lupis

Human

?

?

 

 

Check your answer below.

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Modern Classification System

The basis of the modern system of classification is found in the binomial nomenclature of Linnaeus ans still organizes organisms into a hierarchial system of interrelated groups. Modern taxonomy still uses the form, structure and function of Linnaeus when comparing both living and extinct species (through fossil record). In addition, scientists now incorporate DNA technology and our modern understanding of evolution. Life is organized based on evolutionary relationships and most recent common ancestry. The study of evoltuionary relationships using genetic data is know as phylogentics. The phylogeny of a group of organisms can be displayed visually using a cladogram, which shows shared evolved characteristics. 

 

  

 

An early example of a phylogenetic tree is Darwin's "Tree of Life." 

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Charles Darwin

London 1837

  

Scientists construct a diagram called a cladogram (a tree-like diagram) that shows the evolutionary relationships among organisms. The oldest species, at the bottom of the cladogram, has a common trait that all other species in the cladogram share, while the newest species, at the top of the cladogram, has traits that were more recently developed and that older species do not share.

 

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Cladogram showing the evolutionary relationships of reptiles.

 

 

 Attribution:

Images from paid sbuscription

Darwin's 'Tree of Life' permission from ck12

Cladogram from paid subscription

 

Extend

Check out the video below it helps you learn how to pronounce scientific names and other important information.

 

Try this!

Can you figure out what Linnaeus' system is very similar to write down your guess in your notes.

  

 

Click on the image below and watch the video "Classification", take the graded quiz at the end of the video. Take a screenshot of your graded quiz and submit to the Linnaean Classification System Dropbox.

NOTE: username: gwinnettoc password: brainpop

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 Attribution:

Classification screenshot from paid subscription

 

 

 

 

Evaluate

 

 Driving Question:

What are the Levels of Classification?

 

Tasks

Submission

Required

ENGAGE

  • Complete Animal Classification Game

 

EXPLORE

  • Complete Ordering Activity
  • Review Flash Card Activity

 

 

EXPLAIN

  • Watch powerpoint slideshow on 'The Big Picture'
  • Review information on Classification levels

 

 

EXTEND

  • Watch Classification video.
  • Complete graded quiz, take screenshot of results and submit to 'Linnaean Classification System' dropbox.

 

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