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Classification
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How do we classify? Make observations Choose defining characteristics
Group by those characteristics Divide groups into subgroups by characteristics Continue dividing until each is in its own group
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Why do we classify? Large numbers of objects get very confusing unless they are sorted (prevent confusion) By grouping similar things we can predict patterns (patterns help us make predictions) We can put definite limits on the area of study It helps us discover and point out relationships between objects
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Examples of Classification
Periodic Table- We can get more information about the elements as they are arranged in the periodic table then if they were listed by alphabetical order
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Classification of Organisms
Classification is the arrangement of organisms into orderly groups based on their similarities Classification is also known as taxonomy Taxonomists are scientists that identify & name organisms
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Benefits of Classifying
Accurately & uniformly names organisms Prevents misnomers such as starfish & jellyfish that aren't really fish Uses same language (Latin or some Greek) for all names Sea”horse”?? copyright cmassengale
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Confusion in Using Different Languages for Names
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Latin/Greek Genus species names are Understood by all Taxonomists
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Standardized Naming Binomial nomenclature: Two names for every organism :Genus species Write Genus first, species second Capitalize Genus, lowercase species Italicized in print Underline when writing Names describe characteristics of the organism in Latin or Greek Turdus migratorius American Robin copyright cmassengale
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Binomial Nomenclature
Which TWO are more closely related? copyright cmassengale
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Classification Groups
Taxon ( taxa-plural) is a category into which related organisms are placed There is a hierarchy of groups (taxa) from broadest to most specific Kingdom, Phylum, Class, Order, Family, Genus, species copyright cmassengale
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King Phillip Called Out Fifty Good Soldiers! copyright cmassengale
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Taxons Most genera contain a number of similar species The genus Homo is an exception (its only living members are modern humans) Classification is based on evolutionary relationships copyright cmassengale
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In one order, there are many species
Order Family Genus Species
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Which of these are in the same species? Genus? Kingdom?
German shepherd Poodle Wolf Fox Human Venus flytrap
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Dichotomous Keying Used to identify organisms Characteristics given in pairs Read both characteristics and either go to another set of characteristics OR identify the organism copyright cmassengale
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Example of Dichotomous Key
1a Tentacles present – Go to 2 1b Tentacles absent – Go to 6 2a Eight Tentacles – Octopus 2b More than 8 tentacles – 3 3a Tentacles hang down – go to 4 3b Tentacles upright–Sea Anemone 4a Balloon-shaped body–Jellyfish 4b Body NOT balloon-shaped - 5 copyright cmassengale
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Rule 1 Each step is made of two parts labeled 1A and 1B, then 2A and 2B, and so on. 1a. Bean round ………………………….Garbanzo bean 1b. Bean elliptical or oblong……………………Go to 2 2a.Bean white……………………………White northern 2b.Bean has dark pigments……………………..Go to 3
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Rule 2 When you start a key, your first step is to try and break the objects into two groups about the same size
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Rule 3 Each step either identifies a specimen, or gives directions of the next step to go to. 2a.Bean white……………………………..White northern 2b.Bean has dark pigments…………………….…Go to 3 3a.Bean evenly pigmented……………………….Go to 4 3b.Bean pigmentation mottled……………Pinto bean
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Rule 4 At each step you choose one of the choices, not both.
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Rule 5 When you are writing a set of choices, it is better to use a present/absent choice because it is more inclusive. Use characteristics that are definite.
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The end!
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