The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses. When species are discovered they are given scientific names using the binomial system. All organisms are classified into three domains. Taxonomists classify species using a hierarchy of taxa. The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species. In a natural classification, the genus and accompanying higher taxa consists of all the species that have evolved from one common ancestral species.

1. IBDP core
Topic 5.3
Classification of

2. Understandings:
 The binomial system of names for species is universal among biologists and
has been agreed and developed at a series of congresses
 When species are discovered they are given scientific names using the
binomial system
 All organisms are classified into three domains
 Taxonomists classify species using a hierarchy of taxa
 The principal taxa for classifying eukaryotes are kingdom, phylum, class, order,
family, genus and species
 In a natural classification, the genus and accompanying higher taxa consists of
all the species that have evolved from one common ancestral species
 Taxonomists sometimes reclassify groups of species when new evidence shows
that a previous taxon contains species that have evolved from different
ancestral species
 Natural classifications help in identification of species and allow the prediction
of characteristics shared by species within a group

3. Binomial
System
Source: http://www.bitlanders.com/blogs/introduction-of-binomial-nomenclature/229718

4. Binomial
System

5.  Many attempt were made in the earlier days to classify and name the
animals and plants. Aristotle attempted to classify animals and plants
according to their morphological and anatomical familiarities. He
succeeded so well, that no improvements were made upon his work for
more than 2000 years that is until the time of Linnaeus.
 Linnaeus introduce the system of binomial nomenclature, according to
this system every type of animal and plant shall have a particular name
compounded of two parts, where the first word indicates the genus and
second part the species.
Binomial System

7. Domains
All living organisms are classified into three domains:
 Eukarya – eukaryotic organisms that contain a membrane-bound nucleus
(includes protist, plants, fungi and animals)
 Archaea – prokaryotic cells lacking a nucleus and consist of the
extremophiles (e.g. methanogens, thermophiles, etc.)
 Eubacteria – prokaryotic cells lacking a nucleus and consist of the common
pathogenic forms (e.g. E. coli, S. aureus, etc.)

9. Archaea
 Archaea, (domain Archaea), any of a group of single-celled prokaryotic
organisms (that is, organisms whose cells lack a defined nucleus ) that have
distinct molecular characteristics separating them from bacteria (the other,
more prominent group of prokaryotes) as well as from eukaryotes (organisms,
including plants and animals , whose cells contain a defined nucleus).
Archaea is derived from the Greek word archaios, meaning “ancient” or
“primitive,” and indeed some archaea exhibit characteristics worthy of that
name. Members of the archaea include: Pyrolobus fumarii, which holds the
upper temperature limit for life at 113 °C and was found living in hydrothermal
vents; species of Picrophilus, which were isolated from acidic soils in Japan
and are the most acid-tolerant organisms known—capable of growth at around
pH 0; and the methanogens, which produce methane gas as a metabolic by-
product and are found in anaerobic environments , such as in marshes, hot
springs , and the guts of animals, including humans.

10. Archaea
Source: https://www.britannica.com/science/archaeaarchaea
Archaea at Midway Geyser Basin, Yellowstone National Park, Wyoming.
Wing-Chi Poon

11. Eubacteria

12. Hierarchy of Taxa
Taxonomic rank Mnemonic
Kingdome Karine
Phylum Papikyan
Class Comes
Order Over
Family For
Genus Grape
Species Soda

13. Source: http://ib.bioninja.com.au/standard-level/topic-5-evolution-and-biodi/53-classification-of-biodiv/hierarchy-of-taxa.html

14. The kingdom
Plantae
This kingdome contains 12
phyla – which includes :
Bryophytes,
Filicinophytes,
Coniferophytes and
Angiospermophytes

15. Bryophyta
 Has no vascularisation (i.e. lacks xylem and phloem)
 Has no ‘true’ leaves, roots or stems (are anchored by a root-like structure
called a rhizoid)
 Reproduce by releasing spores from sporangia (reproductive stalks)
 Examples include mosses and liverworts

16. Bryophyta
By Mrs. Mariam Ohanyan

17. Filicinophyta
 Has vascularisation (i.e xylem and phloem)
 Have leaves, roots and stems (leaves are pinnate – consisting of large
fronds divided into leaflets)
 Reproduce by releasing spores from clusters called sori on the underside
of the leaves
 Examples include ferns

18. Filicinophyta

19. Coniferophyta
 Has vascularisation
 Have leaves, roots and stems (stems are woody and leaves are waxy and
needle-like)
 Reproduce by non-motile gametes (seeds) which are found in cones
 Examples include pine trees and conifers

20. Coniferophyta

21. Angiospermophyta
 Has vascularisation
 Have leaves, roots and stems (individual species may be highly variable in
structure)
 Reproduce by seeds produced in ovules within flowers (seeds may
develop in fruits)
 Examples include all flowering plants and grasses

22. Angiospermophyta

23. Plant Phyla Recognition Features:

24. The kingdom Animalia
invertebrates (no backbone)
vertebrates (most chordata)

25. Invertebrates
porifera, cnidaria, platyhelmintha,
annelida, mollusca arthropoda

26. Porifera
 No body symmetry (asymmetrical)
 No mouth or anus (have pores to facilitate the circulation of material)
 May have silica or calcium carbonate based spicules for structural
support
 Examples include sea sponges

27. Porifera

28. Cnidaria
 Have radial symmetry
 Have a mouth but no anus (single entrance body cavity)
 May have tentacles with stinging cells for capturing and disabling prey
 Examples include jellyfish, sea anemones and coral

29. Cnidaria

30. Platyhelmintha
 Have bilateral symmetry
 Have a mouth but no anus (single entrance body cavity)
 Have a flattened body shape to increase SA: Vol ratio and may be
parasitic
 Examples include tapeworms and planaria

31. Platyhelmintha

32. Annelida
 Have bilateral symmetry
 Have a separate mouth and anus
 Body composed of ringed segments with specialisation of segments
 Examples include earthworms and leeches

33. Annelida

34. Mollusca
 Have bilaterial symmetry
 Have a separate mouth and anus
 Body composed of a visceral mass, a muscular foot and a mantle (may
produce shell)
 Examples include snails, slugs, octopi, squid and bivalves (e.g. clams)

35. Mollusca

36. Arthropoda
 Have bilateral symmetry
 Have a separate mouth and anus
 Have jointed body sections / appendages and have a hard exoskeleton
(chitin)
 Examples include insects, crustaceans, spiders, scorpions and centipedes

37. Arthropoda

38. Invertebrate Phyla Recognition Features:

39. Chordata
 Have bilateral symmetry
 Have a separate mouth and anus
 Have a notochord and a hollow, dorsal nerve tube for at least some
period of their life cycle

40. Chordata

41. Chordata
mammals, birds, reptiles,
amphibians fish

42. Vertebrate Classes Recognition Features:

43. Overview of Vertebrate Classes
mammals, birds, reptiles,
amphibians fish

44. Dichotomous Keys
 The identification of biological organisms can be greatly simplified using tools such
as dichotomous keys. A dichotomous key is an organized set of couplets of
mutually exclusive characteristics of biological organisms. You simply compare the
characteristics of an unknown organism against an appropriate dichotomous
key. These keys will begin with general characteristics and lead to couplets
indicating progressively specific characteristics. If the organism falls into one
category, you go to the next indicated couplet. By following the key and making
the correct choices, you should be able to identify your specimen to the indicated
taxonomic level.

45. Dichotomous key
 When using a dichotomous key to identify specimens it is preferable to use
immutable features (i.e. features that do not change)
 Size, colouration and behavioural patterns may all vary amongst individuals
and across lifetimes
 Physical structures (e.g number of limbs) and biological processes (e.g.
reproduction methods) make for better characteristics
Dichotomous keys are usually represented in one of two ways:
 As a branching flowchart (diagrammatic representation)
 As a series of paired statements laid out in a numbered sequence (descriptive
representation)

46. Example 1

47. Example 2

48. Example 3

49. Comparison
of Archaea,
Eubacteria
and Eukarya

50. 2/10/2018By Mrs. Mariam Ohanyan