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• How did you group these items?• Why did you group them this way?

Change Through Time

Classification

Organizing Life’s Diversity

• Biologists want to better understand organisms so they organize them.

• One tool that they use to do this is classification

• Classification is the grouping of objects or information based on similarities.

How Classification BeganHow Classification Began

• Biologists who study taxonomy are called taxonomists.

How Classification BeganHow Classification Began• Taxonomy is the

branch of biology that groups and names organisms based on studies of their different characteristics.

• He classified all the organisms he knew into two groups:

Aristotle’s systemAristotle’s system

• The Greek philosopher Aristotle (384-322 B.C.) developed the first widely accepted system of biological classification.

• animals according to various characteristics, habitat (land,water,air) and physical differences (feet, wings, tails)

Aristotle’s systemAristotle’s system

• plants

herbs, shrubs, and trees

• As time passed, more organisms were discovered and some did not fit easily into Aristotle’s groups, but many centuries passed before Aristotle’s system was replaced.

Aristotle’s systemAristotle’s system

• According to his system, birds, bats, and flying insects are classified together….

– ??? Does that really work ???

– How common are they really?

• Linnaeus’s system was based on physical and structural similarities of organisms.

Linnaeus’s system of binomial nomenclatureLinnaeus’s system of binomial nomenclature

• Swedish botanist, Carolus Linnaeus (1707-1778), developed a method of grouping organisms that is still used by scientists today.

• As a result, the groupings revealed the relationships of the organisms.

• This way of organizing organisms is the basis of modern classification systems.

Linnaeus’s system of binomial nomenclatureLinnaeus’s system of binomial nomenclature

• Eventually, some biologists proposed that structural similarities reflect the evolutionary relationships of species.

• In this system, organisms are name according to their genus and species

• first word = genus

• Second word = species

Linnaeus’s system of binomial nomenclatureLinnaeus’s system of binomial nomenclature

• Binomial nomenclature is a modern classification system using a two-word naming system that Linnaeus developed to identify species.

Linnaeus’s system of binomial nomenclatureLinnaeus’s system of binomial nomenclature

Homo sapiens• italicized in print

• underlined when handwritten

• first letter of the genus name is uppercase

• first letter of the species is lowercase.

Scientific and common namesScientific and common names• Taxonomists are required to

use Latin because:

1. the language does not change

2. a common name can be misleading.

3. it is confusing when a species has more than one common name.

Sycamore tree

buttonwood

common dog

Canus familiaris

• Grouping organisms on the basis of their evolutionary relationships makes it easier to understand biological diversity.

• provides a framework in which to study the relationships among living and extinct species.

Modern ClassificationModern Classification

• Classification systems today are based on evolutionary relationships.

•extinct animals can be included in classification schemes.

How are evolutionary relationships determined?How are evolutionary relationships determined?

• Evolutionary relationships are determined on the basis of:

•similarities in structure

•breeding behavior

•geographical distribution

•chromosomes

•biochemistry

How are evolutionary relationships determined?How are evolutionary relationships determined?

Taxonomy: useful toolsTaxonomy: useful tools

• Cladogram – branching diagram showing evolutionary relationships

Taxonomy: useful tools

• Dichotomous Keys

• Aid in identifying unknown organisms

• Pairs of statements with two choices of characteristics

• Only one choice will apply to the unknown organism

• This will lead to another pair of characteristics.. And so on…

• Largest of Smallest– Kingdom

– Phylum

– Class

– Order

– Gamily

– Genus

– Species

Taxonomic rankingsTaxonomic rankingsDomain

Kingdom

PhylumClass

Order

Family

Genus

Species

1. Put these animals into 3 groups.

2. What characteristics did you use for your system of classification?

Change Through Time

The Six Kingdoms

Organizing Life’s Diversity

• The six kingdoms of organisms are :1. archaebacteria

2. eubacteria3. protists4. fungi5. plants6. animals

The Six Kingdoms of OrganismsThe Six Kingdoms of Organisms

•Prokaryotes - organisms with cells that lack distinct nuclei bounded by a membrane, are microscopic and unicellular.

•There are two kingdoms of prokaryotic organisms: Archaebacteria and Eubacteria.

Bacteria: Archaebacteria and Eubacteria

• Archaebacteria live in extreme environments such as swamps, deep-ocean hydrothermal

vents, and seawater evaporating ponds.

• Most of these environments are oxygen-free.

Bacteria: Archaebacteria and Eubacteria

ProkaryotesProkaryotes• All of the other prokaryotes, about 5000 species of bacteria, are classified in Kingdom Eubacteria.

• Eubacteria have very strong cell walls and a less complex genetic makeup than found in archaebacteria or eukaryotes.

•some cause diseases, most are harmless and many are actually helpful.

Kingdom Protists: A diverse groupKingdom Protists: A diverse group

• A protist is a eukaryote that lacks complex organ

systems and lives in moist environments.

•Unicellular and multicellular

Cilia

Oral groove

Gullet

Micronucleus and macronucleus

Contractile vacuole

A Paramecium

Kingdom Fungi: Earth’s decomposersKingdom Fungi: Earth’s decomposers

• heterotrophs that do not move from place to place.

• A fungus - is either a unicellular or multicellular eukaryote that

absorbs nutrients from organic materials in the environment.

Kingdom Plantae: Multicellular oxygen producers

Kingdom Plantae: Multicellular oxygen producers

• eukaryotic, multicellular, photosynthetic autotrophs.

• None moves from place to place.

Plants: Multicellular oxygen producersPlants: Multicellular oxygen producers

• A plant’s cells usually contain chloroplasts and have cell walls

composed of cellulose.

• Plant cells are organized into tissue that, in turn, are organized into organs and organ

systems.

Kingdom Animalia: Multicellular consumers

Kingdom Animalia: Multicellular consumers

• Animals are multicellular heterotrophs.

• Nearly all are able to move from place to place.

• Animal cells do not have cell walls.

Animals: Multicellular consumersAnimals: Multicellular consumers

• Their cells are organized into tissues that, in turn, are organized into organs and complex organ systems.

Cells Tissue Organs Organ Systems Organisms