Biodiversity
a summary for A Level Biology
Classification of the domestic cat
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Carnivora
Family Felidae
Family Felidae
Genus Felis
Species Felis catus, the domestic cat
Classification of the domestic cat
The five kingdom system
• Until the mid-twentieth century all living organisms were classified in either the Animal Kingdom or the Plant Kingdom
• This led to numerous inconsistencies and absurdities (e.g. bacteria classified as ‘plants’)
• Since the 1960s most biologists have recognised five kingdoms: Prokaryota (Monera), Protoctista, Fungi, Plantae and Animalia
Kingdom Prokaryota (Monera)• All prokaryotic unicells: cells may form groups or
chains, but there is little or no differentiation between them
• Include the bacteria, the cyanobacteria and the archaea:
Nostoc
Sulfolobus
Kingdom Prokaryota (Monera)
• Genetically the bacteria are more different from the archaea than from animals or plants: some biologists propose a three-domain classification, with the Archaea, the Bacteria and the Eukarya having equal ‘domain’ status
The three-domain system
The Prokaryota would comprise two of the domains …the Protoctista contains a wide range of eukaryotes …
with the Plantae, Animalia and Fungi three relatively similar groups.
Kingdom Protoctista
• As we saw in the previous slide, the Protoctista contains a wide range of very diverse organisms
• All are eukaryotic; most are unicellular, and those that are multicellular (e.g. brown or red seaweeds) show very limited cellular differentiation
Kingdom Protoctista
• ‘Animal-like’ Protoctists are often called Protozoa :
Paramecium, a ciliate protozoan
Euglena, a flagellate protozoan
Amoeba, a rhizopod protozoan
Kingdom Protoctista
• ‘Plant-like’ Protoctists are often called Algae :
Chlorella, a ‘green alga’
Assorted phytoplankton
Assorted dinoflagellates
Kingdom Fungi• Fungi are eukaryotic heterotrophic organisms
with cell walls containing chitin and other polysaccharides as well as cellulose
• Typically a fungus consists of a mycelium composed of cylindrical hyphae, which may be multinucleate
• Nutrition is always heterotrophic, either saprobiontic or parasitic
• Reproduction is by production of sexual or asexual spores
Kingdom FungiFalse-colour scanning electron micrograph of Penicillium
Green: hyphae, making up the mycelium
Orange: spore-bearing hyphae (conidiophores)
Blue: asexual spores (conidia)
Kingdom FungiHigher fungi often produce their spores in organised structures called fruiting bodies: these include mushrooms, toadstools, brackets, puffballs etc
Death cap, Amanita phalloides
Shaggy ink cap, Coprinus comatus
Giant puffball, Lycoperdon gigantica
Kingdom Plantae
• Multicellular photoautotrophic eukaryotes• Cell walls contain cellulose• Some cells at least contain chloroplasts
(except in some plant parasites like broomrape or dodder, which have lost them)
Kingdom Animalia
• Multicellular heterototrophic eukaryotes• Cells without cell walls• Usually motile, at least at some stage in the life
cycle• Nutrition is characteristically holozoic• All except sponges show nervous coordination