Classification and Keys

1. ClickBiology
Classification
LOs
•Define and describe the binomial system of
naming species
•Classify the five main classes and describe their
features
•Use simple dichotomous keys based on
features

2. ClickBiology
Starter: Place the following organisms
into groups of your choosing.

3. ClickBiology

4. ClickBiology
Dolphins and sharks
•http://www.youtube.com/watch?v=GmLYGzlPLj0
•http://www.youtube.com/watch?v=QjFqO16w_y4&feature=related

5. ClickBiology
Whales and sharks
Whales and sharks both live in the sea, and could be
considered to look quite similar. However, they are entirely
different species:
Whales and sharks look similar because they have developed structures such as
fins and a streamlined body to help them to live in the sea environment.
whales sharks
have lungs have gills
warm-blooded cold-blooded
give birth to
live young
lay eggs
mammal fish

6. ClickBiology
What is a species?
A group of
organisms that look
the same
A group of
organisms that can
breed
A group of similar
organisms that are
capable of
interbreeding to
produce fertile
offspring
A group of
organisms that look
different but can
breed

7. ClickBiology
What is a species?
A huge variety of organisms live on our planet.
Scientists have put living things into groups to make them
easier to identify. This is called classification.
Organisms can be classified into
different species.
So far, scientists have identified around 290,000 species of
plants, 1,250,000 species of animals and 5 million species of
bacteria living on our planet.
A species is a group of similar organisms
that are capable of interbreeding to
produce fertile offspring.

8. ClickBiology
The grouping together of
animals is called classification.
A group of similar organisms is
called a taxon. The study of
classification is called
taxonomy.

9. ClickBiology
The importance of habitat
Sometimes organisms with a recent common ancestor live in
different environments. They may evolve quite differently, even though their DNA
is similar.
The Galapagos Islands are home to many species
of finch that all evolved from a recent common
ancestor. However, today the finch species have
different features to help them survive on their
particular islands.
Some finches have beaks that are best for eating fruit, while others have beaks
adapted to eating seed or insects. This varies according to what the main source
of food is on the island where they live.

10. ClickBiology
Living in similar habitats
•Organisms that are not closely related
may share several features
•They have to solve the same
environmental problems
Belong to the phylum MolluscaBelong to the phylum Cnidaria

11. ClickBiology
Closely related species can look very different
•The share certain characteristics and are classified close
together but live in very different habitats.
•Habitats determine their features
Arctic fox lives in the arcticFennec fox lives in the desert

12. ClickBiology
Problems with classifying species
Sometimes it is not easy to classify organisms into species.
Bacteria usually reproduce asexually. However, our definition
of ‘species’ is based on organisms that can breed together.
This definition therefore does not work for bacteria.
Many common duck species can breed together to
produce hybrids. There have been over 400 types
of duck hybrid recorded.
These are often fertile, and can breed with each
other or the native ducks, producing ducks with a
variety of characteristics.

13. ClickBiology
Problems with classifying species
Mules are hybrids, made by breeding a donkey with a horse.
Most are infertile, but occasionally female mules do mate with donkeys or horses
to produce offspring. This does not fit with our definition of species, and makes it
hard to classify
the animals.
+ =

14. ClickBiology
62 chromosomes 44 chromosomes
53 chromosomes

15. ClickBiology
Linnaeus (1707-1778)

16. ClickBiology
Binomial classification
The classification system that scientists
use today was developed by
Carl Linnaeus in the 18
th
century.
This system is known as binomial
classification. It uses Latin names, so
scientists around the world can use the
same names without confusion.
The first part of an organism’s scientific name is its genus,
and the second part is the species.
e.g. Tyrannosaurus rex
Genus species

17. ClickBiology
Evolution and classification
Classification enables us to explore the evolutionary origins of
an organism.
Two organisms in the same genus are
generally very similar, and are therefore
likely to share an ancestor in the recent past.
For example, the genus Canis includes
dogs, jackals and wolves.
Two organisms in the same kingdom (e.g. dogs
and spiders) share some characteristics, but are
different in many ways. Consequently, their
common ancestor is likely to be in the distant past.

18. ClickBiology
Evolutionary trees
An evolutionary tree represents the evolutionary relationship
between organisms. Organisms with recent common
ancestors are closer together on the tree.
Scientists use the following evidence to construct
evolutionary trees:
genetics and DNA
fossil records
the structures of organisms
patterns of embryonic
development.

19. ClickBiology
Hierarchical classification system
Kingdom
Phylum
Class
Order
Family
Genus
Species

20. ClickBiology

21. ClickBiology
Prokaryotes
•Unicellular
•Microscopic
•No nuclear membrane

22. ClickBiology
Protoctista
•Eukaryotes
•Mainly single cells.

23. ClickBiology
Plantae
•Multicellular eukaryotes
•Photosynthetic
•Cellulose cell wall.

24. ClickBiology
Fungi
•Heterotrophic eukaryotes
•Rigid cell wall of chitin
•Reproduce by spores

25. ClickBiology
Animalia
•Heterotropic
•Multicellular eukaryotes
•No cell wall
•Nervous coordination

26. ClickBiology
Hierarchical classification system
Kingdom
Phylum
Class
Order
Family
Genus
Species

27. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum
Class
Order
Family
Genus
Species

28. ClickBiology
Animal phylums

29. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum : Chordata (vertebrates)
Class
Order
Family
Genus
Species

30. ClickBiology
Classes of vertebrates
Fish Amphibians Reptiles
Birds Mammals

31. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum : Chordata (vertebrates)
Class : Mammals
Order
Family
Genus
Species

32. ClickBiology
Orders
Rodentia
Carnivora
Proboscidia
Primates

33. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum : Chordata (vertebrates)
Class : Mammals
Order: Primates
Family
Genus
Species

34. ClickBiology
Family

35. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum : Chordata (vertebrates)
Class : Mammals
Order: Primates
Family : Hominidae
Genus
Species

36. ClickBiology
Genus
Pongo Pan
Homo Gorilla

37. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum : Chordata (vertebrates)
Class : Mammals
Order: Primates
Family : Hominidae
Genus : Homo
Species

38. ClickBiology
Species

39. ClickBiology
Hierarchical classification system
Kingdom : Animalia
Phylum : Chordata (vertebrates)
Class : Mammals
Order: Primates
Family : Hominidae
Genus : Homo
Species:
Homo sapiens

40. ClickBiology
Evolutionary tree – mammals
This evolutionary tree shows some examples of mammals.
cow
mouse
rat
platypus
opossum
human
chimp
monkey
horse
dog
Which animal is
most closely related
to the human?
Which animal is
most closely related
to the horse?
Which animal
branched out from
the others furthest
back in evolutionary
time?

41. ClickBiology
Mnemonics to help you remember
the taxons
King
penguins
Climb
Over
Frozen
Grassy
Slopes

42. ClickBiology
Mnemonics to help you remember
the taxons
King
Prawn
Curry
Or
Fat
Greasy
Sausages

43. ClickBiology
Plantae
•Multicellular eukaryotes
•Photosynthetic
•Cellulose cell wall.

44. ClickBiology
Flowering plants are classified into two
groups:
Monocotyledonous plants
1 cotyledon
strap like leaves
parallel veins
flower parts divisible by 3
example: kaffir lily

45. ClickBiology
Flowering plants are classified into two
groups:
Dicotyledonous plants
2 cotyledons
broad leaves
branching veins
flower parts divisible by
4 or 5

46. ClickBiology
Which plant is a monocotyledon and
which is a dicotyledon?
dicotyledon monocotyledon

47. ClickBiology
What about micro-organisms?

48. ClickBiology
Bacteria are single celled organisms
•Bacteria cells are about 1/1000
th
the size of animal or
plant cells.
cell membrane
cytoplasm
DNA
cell wall
slime capsule
made of
peptidoglycans
no nucleus,
DNA is one
long strand
kept in the
cytoplasm

49. ClickBiology
Prokaryotes
•Unicellular
•Microscopic
•No nuclear membrane

50. ClickBiology
The main body of a fungus is the
mycelium, which is made of hyphae
•Fungal cells have cell walls made of substances
such as chitin
Mucor
growing on
moist bread
hyphae of Mucor
mycelium:
Secrete digestive
enzymes
sporangium containing sporesmushroom
spores produced here
hyphae of mushroom
mycelium

51. ClickBiology
Viruses are not classified as living
things as they are not made of cells
•Viruses are very small, approximately 100nm
across (1nm = 1/1000 000 of a mm)
proteins of the
virus coat
RNA
cross section of the human immunodeficiency virus (HIV)
10nm

52. ClickBiology
Viruses reproduce by invading other
cells
1. Virus attaches
to cell membrane
2. Virus RNA
enters cell
3. DNA copy of
the RNA is made
4. Nucleus
makes copies of
the virus RNA
5. Virus cores
are made in the
cytoplasm
6. New viruses
leave the cell
White blood cell (lymphocyte)

53. ClickBiology
Using the book (Pg 5, 6 ,7)…
Practice at Classifying
different Invertebrates…
EXT: Make a Key to identify unknown
organisms…?

54. ClickBiology
Biological classification:
Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Chordata
Mammalia
Carnivore
Felidae
Panthera
pardus
Taxonomic
ranks
Panthera pardus

55. ClickBiology
The binomial system gives organisms a two word
name showing the genus and species
Panthera leo Panthera tigrisPanthera pardus
Genusspecies GenusGenus speciesspecies

56. ClickBiology
There are other classification systems:
•Cladistics:
Based on similarity and differences
between DNA and RNA sequences
Extended
AAAA
AACA
AGAA
AGTA
AGGA

57. ClickBiology
You will need to be able to:
•Define and describe the binomial system of naming
species
•Use a dichotomous key to identify an unknown organism

58. ClickBiology
Keys use a series of questions to identify
unknown organisms
1.Stalk does not have a frillgo to 2
Stalk has a frill go to 3
2.Stem is brown Fungus A
Stem is yellow Fungus B
3.Cap has spots go to 4
Cap does not have spotsFungus C
4.Cap is red Fungus D
Cap is brown Fungus E

frill
cap
Identify the fungus

59. ClickBiology
Now you should be able to
•Define and describe the
binomial system of naming
species
•Use a dichotomous key to
identify an unknown
organism