Classification of Organisms

Question 1

Why is it important to correctly identify and communicate organisms?

Answer 1

So scientists around the world know specifically what another scientist is talking about.

Question 2

What is taxonomy?

Answer 2

The science of classifying organisms according to the inferred relationships
- artificial means by which we can deal with huge biodiversity and organize organisms so that relationships can be made

Question 3

Two main purposes of biological classification

Answer 3

1) identify organisms
2) provide a basis for recognizing natural grouping of living things
- the current system of classification is the binomial system of nomenclature developed by Carl Linnaeus

Question 4

Binomial Nomenclature

Answer 4

• A method of naming organisms by using two names - the genus name and the species name
• based on an organism’s physical and structural features (assumption that the more features that organisms have in common, the closer their relationship)
• Genus: always cap
• Species: always lowercase
• both are italicized or underlined to make them stand out in written text

Question 5

Why is binomial nomenclature based in Greek and Latin?

Answer 5

Latin is considered a ‘dead’ language (this does not mean it is not spoken it means that it doesn’t evolve. Because it doesn’t evolve Latin is the universal language of science and anyone in any part of the world will be able to understand the binomial Latin name of an organism.

Question 6

Order of Genus and Species

Answer 6

• Genus then species
• genus may appear alone (as it can contain many different species) however, the species can never be alone (as it is the lowest level of classification)

Question 7

The 7 class system

Answer 7

• the genus and species are pat of 7 main taxa
• taxa: categories used to define organisms
• each level becomes more specific as one goes from top to bottom
• the increase in similarities are in anatomy, embryology, and ancestry
• as you go down the pyramid you increase in similarity but decrease in number
  Kingdom
  Phylum
  Class
  Order
  Family
  Genus
  Species

Question 8

Development of Kingdoms

Answer 8

• originally was only a two class system made of plantae and animalia
• discovery of single-celled organisms that have plant and animal traits led to third kingdom called Protista or Protocista
• Because bacteria and cyanobacteria lacked a true nucleus (ie prokaryotes meaning before nucleus) a fourth kingdom was made called monera was formed
• it acknowledged that mushrooms were different enough from plants to be placed in its own kingdom called Fungi

Question 9

After the 5 kingdom system

Answer 9

Carl Woese and other researchers had discovered that a group called archaebacteria (‘ancient’) was significantly different from bacteria (now called eubacteria meaning ‘true’ bacteria)
- this replaced the Kingdom monera into archaebacteria and eubacteria

Question 10

Domains

Answer 10

• classification of organisms have been split into three domains
  1) Eukarya: eukaryotes, eu meaning true and karyotes meaning nucleus, contains the kingdoms anamalia, plantae, fungi, and protista
  2) archea: archaebacteria
  3) bacteria: eubacteria

Question 11

Eubacteria

Answer 11

General Characteristics
- simple organisms lacking a nucleus meaning they are prokaryotic
- either heterotrophs or autotrophs
- all can reproduce asexually
- they live nearly everywhere
Cell Wall
- often have a cell wall
- made of peptidoglycan which is made of protein and subunits
Representative Organism
- bacteria
- cynobacteria

Question 12

Archaebacteria

Answer 12

General Characteristics
- prokaryotic
- heterotrophs
- live in salt lakes, animal guts, and hot springs
Cell Wall
- has a cell wall
- does not contain peptidoglycan
Representative Organisms
- methanogens
- extreme thermophiles
- extreme halophiles

Question 13

Protista

Answer 13

General Characteristics
- most are unicellular some multicellular
- some are autotrophs some are heterotrophs some are both
- reproduce sexually and asexually
- live in aquatic and moist habitats
Cell Wall
- no cell well
Representative Organisms
- algae
- protozoans

Question 14

Fungi

Answer 14

General Characteristics
- most are multicellular
- all are heterotrophs
- reproduce sexually and asexually
- most are terrestrial
Cell Wall
- present and made of chitin
Representative Organisms
- mushrooms
- yeasts
- bread molds

Question 15

Plantae

Answer 15

General Characteristics
- all are multicellular
- all are autotrophs
- reproduce sexually and asexually
- most are terrestrial
Cell Wall
- present and made of cellulose
Representative Organisms
- mosses
- ferns
- conifers
- flowering plants

Question 16

Animalia

Answer 16

General Characteristics
- all are multicellular
- all are heterotrophs
- most reproduce sexually
- live in terrestrial and aquatic habitats
Cell Wall
- absent
Representative Organisms
- sponges
- worms
- lobsterss
- starfish
- fish
- reptiles
- birds
- mammals

Question 17

Phylogeny

Answer 17

• the history of a group of species or a group of organisms
• this relationship can be represented in a phylogenetic tree where the tree starts from the most ancestral form and branches out to all other descendants
• normally the branch lengths are proportional to the predicted evolutionary time between organisms and sequences

Question 18

Dichotomous Key

Answer 18

• a two part key that is used to identify living things
• Greek meaning ‘divided into two things’
• consists of 2 part statement describing a single characteristic of an organism
• at each step the user is directed to another part depending upon the choice
• these characteristics should not be vague or subjective and should have only one possible answer
  there are two types
  1) branch method
  2) list method