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Classification

Dichotomous Key

1. A way to identify unknown organisms 2. Contains major characteristics of

groups of organisms

3. Pairs of CONTRASTING descriptions 4. After each description key either directs

use to another pair of descriptions or identifies an object

Section 1: The Importance of Classification

Taxonomy: the science of describing, naming, and classifying organisms

Genus: a level of classification that

contains similar species

Binominal Nomenclature: a system of giving each organism a two-word scientific name that consists of the genus name followed by the species name

I. The Need for Systems

A. About 1.7 million species have been named and described by scientists

B. Millions more are undiscovered

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C. Practice of naming and classifying organisms is taxonomy

D. Taxonomic systems organize

knowledge of organisms E. Systems attempt to provide consistent

ways to name and categorize organisms

F. Taxonomic systems do not use common names

1. May be confusing because common names

are different places 2. Use categories to organize organisms

Cambaridae camburus

n Crayfish n Crawdad n Mudbug n Yabbie

G. Biologists group organisms into large categories

1. Then smaller, more specific categories

a. taxon (plural, taxa.)

II. Scientific Nomenclature

A. Various naming systems were invented in the early days of European biology

1. Used long, descriptive Latin phrases called

polynomials

2. Names for taxa were inconsistent between these systems 3. The only consistent taxon was genus

a. used to group similar species

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B. Carlos Linnaeus

1. Swedish Biologist in the 1750s 2. Carl von Linne 3. Developed simpler and more consistent system

4. Two-word naming system called binomial nomenclature 5. Genus name and a single descriptive word for each species 6. Universally adopted 7. Called a scientific name

C. Naming Rules

1. No two species can have the same scientific name 2. All scientific names are made up of two Latin

or Latin-like terms

3. All the members of a genus share the genus name as the first term Lion - Panthera leo Tiger - Panthera tigris

4. The second term is called the species

identifier, and is often descriptive 5. When you write the scientific name, the genus

name should be capitalized and the species identifier should be lowercase

6. Both terms should be italicized (or underlined) 7. Example

A. Apis mellifera is the European honeybee

1) The term mellifera derives from the latin word for honey

III. The Linnaean System

A. Devised a system to classify all plants and animals that were known

B. Organisms grouped at successive levels

of the hierarchy based on similarities in form and structure

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C. Eight basic levels of modern classification

1. Domain 2. Kingdom 3. Phylum (Division--Plants) 4.  Class 5.  Order 6.  Family 7.  Genus 8.  species (strains - Bacteria)

Dumb Kings Play Chess On Finely Ground Sand

D. Classification of Man

1. Domain Eukarya 2. Kingdom Animalia 3. Phylum Chordata 4. Class Mamalia 5. Order Primates 6. Family Hominidae 7. Genus Homo 8. species Homo sapiens

D. Each taxon is identified based on shared traits

E. Similar species are grouped into a

genus

1. Similar genera are grouped into a family 2. And so on up to the level of domain

F. Domain

1. Recent addition 2. Recognizes most basic differences among

cell types 3. All living things grouped into one of three

domains

G. Kingdom

1. Six kingdoms fit within the three domains

H. Phylum 1. Subgroup within kingdom

I. Class

1. Subgroup within a phylum

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J. Order

1. Subgroup within a class

K. Family

Subgroup within an order

L. Genus (plural, genera)

1. Subgroup within family

M. species

1. Subgroup within Genus 2. Uniquely shared traits 3. Species are thought to be closely related

4. Defined as a unique group of organisms united by heredity or the ability to interbreed

5. Scientists tend to define species based on

unique features 6. Example

1. Homo sapiens

a. only living primate species that walks upright b. uses spoken language

Section 2: Modern Systematics

Phylogenetic Tree: shows the evolutionary relationships among organisms

I. Evolutionary Relationships

A. Phylogenetic Tree: family tree used by taxonomists

1. Shows evolutionary relationships among

species not individuals

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2. Fossil Record Used 3. Comparative to family members 4. Spirochetes are most closely related to what

organisms?

Proteobacteria

5. Name two organisms that are distantly related 6. Classification of organisms is based on

GENETIC relationship 7. Organisms that are more closely related have

similar genetic makeup and therefore have a recent common ANCESTOR

II. Physical Structures

A. Linnaeus based his classification on physical characteristics

B. Modern scientists base classification on

physical and chemical characteristics as well as fossil record

III. Problems in Classification

A. As new evidence is discovered and new research is done scientists are having to reclassify organisms

Section 3: Kingdoms and Domains

Bacteria: extremely small, single-celled organisms that usually have a cell wall and that usually reproduce by cell division: members of the domain Bacterial

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Archaea: prokaryotes that are distinguished from other prokaryotes by differences in their genetics and in the makeup of their cell wall; members of the domain Archaea

Eukaryote: an organisms made up of cells that have a nucleus enclosed by a membrane, multiple chromosomes, and a mitotic cycle; members of the domain Eukarya

I. Updating Classification Systems

A. When Linnaeus created his system he recognized two kingdoms:

1. Plantae 2. Animalia

B. Biologists have added complexity and detail to classification systems as they have learned more

1. Many taxa have been proposed

2. Some have been reclassified

a. Sponges used to be classified as plants b. Microscopes allowed scientists to study sponge

cells c. Scientists learned that sponge cells are much more

like animal cells, so today sponges are classified as animals

C. 1800s added Kingdom Protista as a taxon for unicellular animals

D. Then noticed differences between

prokaryotic and eukaryotic cells

1. Scientists created Kingdom Monera for prokaryotes

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E. By the 1950s, Kingdoms Monera, Protista, Fungi, Plantae, and Animalia were used

F. In the 1990s, genetic data suggested two major

groups of prokaryotes

1. Kingdom Monera split into Kingdoms

a. Eubacteria b. Archaebacteria

II. The Three-Domain System

A. Divide all organisms into three domains

1. Bacteria 2. Archaea 3. Eukarya

B. Major taxa are defined by major characteristics, including

1. Cell Type

a. Prokaryotic b. Eukaryotic

2. Cell Walls

a. Absent b. Present

3. Body Type

a.  Unicellular

b. Multicellular

4. Nutrition

a . Autotroph (makes own food) b. Heterotroph (gets nutrients from other organisms

5. Related groups of organisms have similar

a. Genetic Material

b. Systems of genetic expression

C. Bacteria

1. Prokaryotes 2. Strong exterior walls and a unique genetic

system

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3. Same kind of cell membrane lipid as most eukaryotes do

4. All bacteria are similar in structure, no

internal compartments

5. Classified according to

a. Their shape b. Nature of their cell wall c. Their type of metabolism d. How they obtain nutrients

6. Most abundant organisms on Earth 7. Found in every environment

D. Archea

1. Chemically unique cell wall and membranes 2. Unique genetic system

a. Share some similarities with those of eukaryotes that they do not share with those of prokaryotes

3. Scientists think that archea evolved in a separate lineage from bacteria early in Earth’s history

4. Scientists also believe that some archea

eventually gave rise to eukaryotes

5. First found in extreme environments

a. Salt Lakes b. Deep ocean c. Hot springs that exceeded 100 °C d. These archaea are called extremophiles e. Methanogens live in oxygen-free environments

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E. Eukarya is made up of Kingdoms

1. Protista 2. Fungi 3. Plantae 4. Animalia 5. Eukaryotes

6. Cells have a complex inner structure that enabled cells to become larger than the earliest cells

7. Complex inner structure enabled the evolution

of multicellular organisms

8. True multicellularity and sexual reproduction 9. Major groups of eukaryotes are defined by

1. Number of cells 2. Body organization 3. Types of nutrition

F. Plantae

1. Almost all plants are autotrophs

a. The process that makes food, photosynthesis, occurs in chloroplasts

2. Cell wall is made of a rigid material called cellulose

3. More than 350,000 known species of plants

exist

G. Animalia

1. Multicellular heterotrohps 2. Their bodies may be simple collections of cells

or complex networks of organ systems

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3. Animal cells lack a rigid cell wall 4. More than 1 million known species of

animals exist

H. Fungi

1. Heterotrophs that are mostly multicellular 2. Cell wall is made of a rigid material called

chitin 3. More than 70,000 known species of fungi

exist

I. Protista

1. A “leftover” taxon, it is a diverse group 2. Any eukaryote that is not a plant, animal, or

fungi can be called a protist 3. Did not descend from a single common

ancestor

4. Biologists recognize four major groups of protists:

a. Flagellates b. Amoeba c. Algae d. Parasitic protists

5. Recently, biologists have proposed to replace

Protista with several new kingdoms

Natural Selection Review

I. Define natural selection

A. Survival and Reproduction of organisms best adapted to the environment

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B. List the four parts of natural selection

1. There is variation within populations 2. Some variations are favorable 3. Not all offspring survive 4. Individuals that survive & reproduce are those

with favorable variations

Use the table below to answer the following questions:

Level Dog Wolf Human House Cat Octopus Anteater Kingdom Animalia Animalia Animalia Animalia Animalia Animalia Phylum Chordata Chordata Chordata Chordata Molluska Chordata Class Mammalia Mammalia Mammalia Mammalia Cephalopoda Mammalia Order Carnivora Carnivora Primate Carnivora Octopoda Edentata Family Canidae Canidae Hominidae Felidae Octopodidae Myrmecophagidae Genus Canis Canis Homo Felis Octopus Myramecophaga Species familiaris lupus sapiens domesticus vulgaris tridactyla

a. Which organisms on the table are most closely related?

b. Which level of classification is your

answer based on?

Dog - Wolf

Species

c. Which organisms on the table is the most distantly related to the others?

d. Which level of classification is your answer base on?

Octopus

Phylum