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Taxonomy – study of classifying organisms
- Taxonomists are scientists who study classifying
- Taxon ( taxa-plural) is a category into which related organisms are placed
Reasons to Classify:
- Shows evolutionary relationships
- Accurately & uniformly names organisms
- Prevents misnomers such as starfish & jellyfish that aren’t really fish
- Uses same language (Latin) for all names
- Prevents duplicated names because all names must be approved by International Naming Congresses (International Zoological Congress)
- Naming rules are followed called the International Code for Binomial Nomenclature
- Aristotle was the first taxonomist dividing organisms into land, sea, & air dwellers
- John Ray was the first to use Latin for naming
- Linnaeus developed the modern system of naming known as binomial nomenclature, a two-word name (Genus & species)
- Scientific names should be italicized in print or underlined when writing
- Always capitalize the genus name, but write the species in lower case
- The scientific name for man is Homo sapiens
- The genus name may be abbreviated, but not the species (H. sapiens)
- Linnaeus placed organisms into related groups called taxa (taxon-singular) based on their morphology (similar structure & function)
- The broadest taxon is called the kingdom
- Linnaeus put all organisms into one of two kingdoms — Plantae or Animalia
- The other six taxa from broadest to most specific are — Phylum, Class, Order, Family, Genus, & species
- A sentence to help remember these taxa is — “King Phillip Came Over For Gooseberry Soup.”
- Each taxa is a proper noun &should be capitalized except species
- Each level or taxon groups together organisms that share more characteristics than the level above
- Botanists use the term division instead of phylum for classifying plants
- Plant species are subdivided into varieties, while bacteria are subdivided into strains
Basis for Modern taxonomy:
- Modern taxonomists classify organisms based on their evolutionary relationships
- Homologous structures have the same structure, but different functions & show common ancestry
- The bones in a bat’s wing, human’s arm, penguin’s flipper are the same (homologous), but the function is different
- Analogous structures have the same function, but different structures & do not show a close relationship (insect wing & bird’s wing)
- Similarity in embryo development shows a close relationship (vertebrate embryos all have tail & gill slits)
- Similarity in DNA & amino acid sequences of proteins show related organisms
Modern Taxonomic System:
- Modern taxonomy uses six kingdoms — Archaebacteria, Eubacteria, Protista, Fungi, Plantae, & Animalia
- Archaebacteria & Eubacteria are unicellular prokaryotes lacking a nucleus, while Protista, Fungi, Plantae, & Animalia are all eukaryotes with a nucleus & membrane-bound organelles
- All members of Plantae & Animalia are multicellular organisms
- Fungi & Animalia are heterotrophs, while Plantae are all autotrophs capable of making their own food
- Archaebacteria live in harsh environments like very salty lakes; intestines of mammals; and hot, sulfur springs & may be autotrophs or heterotrophs
- Eubacteria are true bacteria some of which cause disease
- Protista are mainly unicellular with a few multicellular organisms and may be autotrophic (Euglena) or heterotrophic (Ameba)
- Fungi include multicellular mushrooms, mold, unicellular yeast, etc. & are absorptive heterotrophs (digest food & then absorb it)
- Animalia are ingestive heterotrophs that take in food & then digest it inside their multicellular bodies.
- Plantae includes all plants & are the only all multicellular, autotrophic kingdom
Phylogeny (evolutionary history):
- Phylogenetic trees are branching diagrams showing how organisms are related
- Also called family trees
- Fossil records help establish relationships on a phylogenetic tree
- Organizes living things based on their evolution (systematics)
- Common ancestor is shown at the base of the tree
- Most modern organisms shown at tips of branches
- Each time a branch divides into a smaller branch, a new species evolves
- Cladograms shows how organisms are related based on shared, derived characteristics such as feathers, hair, scales, etc.
Three Domain System:
- Based on comparing sequences of ribosomal RNA in different organisms to determine ancestry
- All organisms placed into three broad groups called domains
- Domain Archaea (kingdom Archaebacteria) contains chemosynthetic bacteria living in harsh environments
- Domain Bacteria (kingdom Eubacteria) contains all other bacteria including those causing disease
- Domain Eukarya (kingdoms Protista, Fungi, Plantae, & Animalia) contains all eukaryotic organisms
1. How many known species are there?
2. What percent of all organisms that have ever lived is this?
3. Are all organisms on Earth today identified?
4. Define classification.
5. What is another term for classification?
6. What do you call scientists that study classification?
7. Classifying organisms makes naming organisms more _____________ and _____________.
8. Classifying prevents ____________ or inaccurate naming.
9. Give two examples of misnomers and explain why they aren’t correct.
10. What language is used for scientific naming?
11. Sometimes, scientific names may be ___________ instead of Latin.
12. Why don’t scientists around the world just use more simple, common names for organisms?
13.What language is universally used by scientists for naming?
14. Who was the first taxonomist and what two groups did he place organism in?
15. How did Aristotle subdivide his two groups?
16. Who was first to use Latin for scientific naming?
17. What was the problem with Ray’s names?
18. What 18th century taxonomist developed the naming system still used today?
19. How did Linnaeus group his organisms?
20. Who is the “father of taxonomy”?
21. What is Linnaeus’s naming system called?
22. Explain binomial nomenclature.
23. Besides Latin, what other language is sometimes used for scientific names?
24. How do scientific names appear in print?
25. What must be done to a scientific name when you are writing it?
26. Give an example of a common and scientific name for an animal.
27. Where can you find the rules for naming organisms?
28. All scientific names must be approved by ________________ ___________ ______________.
29. Why do naming congresses have to approve names?
30. What is a taxon?
31. What is plural for taxon?
32.There is a ______________ of groups that goes from the broadest grouping to the most _____________ grouping.
33. Name the 8 taxon in order from broadest to most specific.
34. What is the NEWEST and BROADEST taxon?
35. Instead of the taxon phylum, what other taxon is used for plants at this level?
36. What is the most specific taxon?
37. Write the sentence used to help remember the 8 most important taxonomic levels.
38. Complete the following taxonomic table:
|Classification for Humans|
Domains of Organisms
39. How many domains are there?
40. Name the 3 Domains.
41. What are the main characteristics of Archaea and Eubacteria?
42. What are the main characteristics of the Domain Eukarya?
43. What Domain of organisms probably evolved first?
44. Where do Archaea live? Give some examples.
45.Name an Archaean.
46. Where are eubacteria found?
47. Some bacteria cause ______________ but many act as decomposers & are important to the ______________.
48. Some members of eubacteria live in the __________ of animals.
49. The Domain Eukarya is divided into how many kingdoms?
50. List the 4 kingdoms of Eukarya and tell what organisms are in each group.
51. Which 2 kingdoms contain all multicellular members?
52. List the main characteristics of the Kingdom Protista.
53. Microscopic organisms found in pond water are most likely in the kingdom _______________.
54. All members of the Kingdom Fungi are _____________ except for unicellular ____________.
55. What type of heterotrophic organism are fungi?
56. Explain what it means to be an absorptive heterotrophic.
57. The cell walls of fungi are made of ______________.
58. Members of the kingdom Plantae are all ________________ and _____________.
59. What do plants use as their energy to make food?
60. Name the food making process of plants.
61. Plant cell walls are made of _______________.
62. Members of the Kingdom Animalia contain all of the multicellular _____________ on Earth.
63. Animals are ______________ heterotrophs that feed on __________ or other __________.
64. Define ingestive heterotroph.
65. Complete the following table for characteristics of each kingdom:
|Kingdom||Organization||Type of Nutrition||Examples|
66. A Genera may contain a number of different ___________.
67. What Genera is an exception to this?
68. Which Kingdom has the largest number of different kinds of organisms?
69. What two groups are in the plant kingdom?
Basis for Modern Taxonomy
70. List three examples of things used as a basis for modern taxonomy.
71. What are homologous structures?
72. What is an embryo?
73. At the molecular level, similarities in ___________, __________, or the __________ __________ sequence of proteins can be a basis for grouping organisms together.
74. Give an example of homologous structures show similarities among organisms in the same taxon.
75. Name 5 organisms that have similar embryonic development. To what taxon do these organisms belong?
76. What is a cladogram?
77. Using the following cladogram, name the organisms that share 4 of the 5 characteristics.
78. What characteristic(s) do the grouper and lamprey share?
79. What characteristic is found in all the animals EXCEPT the lancelet?
80. What is a dichotomous key?
81. When using a dichotomous key, you should make sure you ___________ both characteristics and either ____________ the organism OR go to ____________ set of characteristics.
82. Use the following dichotomous key to identify the picture of each organism.
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
|Dichotomous Key to Salamanders|
A dichotomous key is constructed of a series of couplets, each consisting of two separate statements. For example: couplet 1. Seeds round soybeans
1. Seeds oblong 2 (this statement indicates that you go to couplet “2”)
couplet 2. Seeds white northern beans
2. Seeds black black beans
By reading the two statements of each couplet, you progress through the key from typically broad characteristics to narrower characteristics until only a single choice remains. As long as the correct statement of each couplet is chosen, and the unknown organism is included in the key, a confident identification is usually achieved. Many types of organisms can be identified using a dichotomous key. In this lab, you will identify salamanders.
pictures of various salamanders, dichotomous key, metric ruler, pencil
- Use the dichotomous key provided to identify the salamanders in Figure 1.
- Write the pathway you took to get to the name of the salamander next to the drawing.
- Write the correct name for the salamander on the line below each picture.
Figure 1 – Types of salamanders
Key to the Salamanders:
|1||a||Hind limbs absent||Siren|
|b||Hind limbs present||Go to 2|
|2||a||External gills present in adults||Mud puppy|
|b||External gills absent in adults||Go to 3|
|3||a||Large size (over 7 cm long)||Go to 4|
|b||Small size (under 7 cm long)||Go to 5|
|4||a||Body background black, large white spots irregular in shape and size completely covering body & tail||Tiger salamander|
|b||Body background black, small, round, white spots in a row along each side fro eye to tip of tail||Spotted Salamander|
|5||a||Body background black with white spots||Go to 6|
|b||Body background light color with dark spots and or lines on body||Go to 7|
|6||a||Small white spots on a black background in a row along each side from head to tip of tail||Jefferson salamander|
|b||Small white spots on a scattered throughout a black background from head to tip of tail||Slimy salamander|
|7||a||Large irregular black spots on a light background extending from head to tip of tail||Marbled salamander|
|b||No large irregular black spots on a light background||Go to 8|
|8||a||Round spots scattered along back and sides of body, tail flattened like a tadpole||Newt|
|b||Without round spots and tail not flattened like a tadpole||Go to 9|
|9||a||Two dark lines bordering a broad, light mid-dorsal stripe with a narrow median dark line extending from the head onto the tail||Two-lined salamander|
|b||Without two dark lines running the length of the body||Go to 10|
|10||a||A light stripe running the length of the body and bordered by dark pigment extending downward on the sides||Red-backed salamander|
|b||A light stripe extending the length of the body, a marked constriction at the base of the tail||Four-toed salamander|