ClassificationClassification• Carolus Linnaeus, a Swedish naturalist, Carolus Linnaeus, a Swedish naturalist,

developed a new system of grouping developed a new system of grouping organisms that was accepted and used by organisms that was accepted and used by most scientists. most scientists.

• His classification system was based on His classification system was based on looking for organisms with similar looking for organisms with similar structures. structures.

• Linnaeus also developed a scientific Linnaeus also developed a scientific naming system that is still used today. naming system that is still used today.

Binomial NomenclatureBinomial Nomenclature

• The two-word naming system that The two-word naming system that Linnaeus used to name various Linnaeus used to name various organisms is called organisms is called binomial binomial nomenclaturenomenclature (bi NOH mee ul · NOH (bi NOH mee ul · NOH mun klay chur). mun klay chur).

• This two-word name is an organism’s This two-word name is an organism’s species.species.

Ambystoma

genus

Binomial NomenclatureBinomial Nomenclature

• The first word of the two-The first word of the two-word name identifies the word name identifies the genus of the organism.genus of the organism.

• A A genusgenus is a group of similar is a group of similar species. species.

• The second word of the name The second word of the name usually describes a feature. usually describes a feature.

tigrinum

feature

Uses of Scientific NamesUses of Scientific Names

• Scientific names are used for four Scientific names are used for four reasons. reasons.

• First, they help avoid mistakes. First, they help avoid mistakes.

• Often, common names for two different Often, common names for two different organisms are the same. organisms are the same.

• Scientific names help distinguish between Scientific names help distinguish between those organisms. those organisms.

Uses of Scientific NamesUses of Scientific Names

• Second, organisms with similar Second, organisms with similar evolutionary histories are classified evolutionary histories are classified together. together.

• Third, scientific names give descriptive Third, scientific names give descriptive information about the species. information about the species.

•Fourth, scientific names allow information Fourth, scientific names allow information about organisms to be organized easily and about organisms to be organized easily and efficiently.efficiently.

Uses of Scientific NamesUses of Scientific Names• The classification of the bottle-nosed The classification of the bottle-nosed

dolphin shows that it is in the order dolphin shows that it is in the order Cetacea. Cetacea.

Modern ClassificationModern Classification

• Like Linnaeus, modern scientists use Like Linnaeus, modern scientists use similarities in structure to classify similarities in structure to classify organismsorganisms.

• They also study fossils, hereditary They also study fossils, hereditary information, and early stages of information, and early stages of development. development.

Modern ClassificationModern Classification• Phylogeny Phylogeny (fi LAH juh nee) is the (fi LAH juh nee) is the

evolutionary history of an organism, that evolutionary history of an organism, that is, how the organism has changed over is, how the organism has changed over time. time.

• Today, it is the basis for the classification Today, it is the basis for the classification of many organisms. of many organisms.

•In the classification system used today, the In the classification system used today, the smallest group is a smallest group is a speciesspecies..

•There are broader groups preceding There are broader groups preceding species, the largest of which is a species, the largest of which is a kingdomkingdom..

Modern ClassificationModern Classification

• Some scientists have proposed that before Some scientists have proposed that before organisms are grouped into kingdoms, organisms are grouped into kingdoms, they should be placed in larger groups they should be placed in larger groups called domains. called domains.

• One proposed system groups all One proposed system groups all organisms into three domains. organisms into three domains.

Tools for Identifying OrganismsTools for Identifying Organisms• Scientists use field guides and

dichotomous (di KAH tuh mus) keys to identify organisms.

•A dichotomous key is a detailed list of identifying characteristics that includes scientific names.

MULTIPLE CHOICEMULTIPLE CHOICE1. ___ PHYLOGENY TELLS1. ___ PHYLOGENY TELLS

A. How an organism is different from other A. How an organism is different from other organisms.organisms.

B. How an organism has changed over time B. How an organism has changed over time

C. How an organism received its two part C. How an organism received its two part scientific namescientific name

D. How Linnaeus started binomial D. How Linnaeus started binomial nomenclature.nomenclature.

BB

MULTIPLE CHOICEMULTIPLE CHOICE2. ___ The smallest group in the 2. ___ The smallest group in the classification system used today is called aclassification system used today is called a

A. FamilyA. Family

B. GenusB. Genus

C. KingdomC. Kingdom

D. SpeciesD. SpeciesDD

MULTIPLE CHOICEMULTIPLE CHOICE3. ___ Linnaeus developed a system of 3. ___ Linnaeus developed a system of grouping organisms that was accepted by grouping organisms that was accepted by most scientists. He grouped organisms with most scientists. He grouped organisms with _______ together._______ together.

A. Dichotomous keysA. Dichotomous keys

B. Similar structures B. Similar structures

C. Similar fossilsC. Similar fossils

D. Similar hereditary informationD. Similar hereditary information

BB

MULTIPLE CHOICEMULTIPLE CHOICE4. ___ Organisms that can mate and 4. ___ Organisms that can mate and reproduce fertile offspring belong to the reproduce fertile offspring belong to the same ______same ______

A. SpeciesA. Species

B. GenusB. Genus

C. KingdomC. Kingdom

D. DomainD. Domain

AA

SHORT ANSWERSHORT ANSWER

5. What is binomial nomenclature?5. What is binomial nomenclature?

AnswerAnswer

A two word naming system that Linnaeus A two word naming system that Linnaeus used to name organisms and is now used in used to name organisms and is now used in modern classificationmodern classification

6. Explain three reasons scientific names 6. Explain three reasons scientific names are usefulare useful AnswerAnswerAny 3: 1) They help avoid mistakes and Any 3: 1) They help avoid mistakes and confusion since each scientific name refers confusion since each scientific name refers to only one kind of organism. 2) They help to only one kind of organism. 2) They help show which organisms are related because show which organisms are related because organisms with similar evolutionary organisms with similar evolutionary histories are grouped together. 3) They give histories are grouped together. 3) They give descriptive information about species. 4) descriptive information about species. 4) They allow information about organisms to They allow information about organisms to be organized easily and efficientlybe organized easily and efficiently