Biological Classification – Vocabulary Review

Biological classification

Systematic grouping of organisms based on shared characteristics and evolutionary relationships.

Aristotle's classification

Earliest scientific scheme dividing plants into trees, shrubs, herbs and animals into those with and without red blood.

Two-kingdom system

Linnaeus’ scheme placing all organisms in Kingdom Plantae or Kingdom Animalia.

Whittaker's five-kingdom classification

1969 system dividing life into Monera, Protista, Fungi, Plantae and Animalia using cell type, body organisation, nutrition, reproduction and phylogeny.

Kingdom Monera

Kingdom comprising all prokaryotic organisms, chiefly bacteria.

Kingdom Protista

Kingdom of mostly unicellular eukaryotes such as algae, protozoa and slime moulds.

Kingdom Fungi

Eukaryotic, heterotrophic organisms with chitinous cell walls that absorb nutrients; includes moulds, yeasts and mushrooms.

Kingdom Plantae

Multicellular, photosynthetic, cellulose-walled eukaryotes commonly called plants.

Kingdom Animalia

Multicellular, heterotrophic, cell-wall-less eukaryotes that ingest food.

Archaebacteria

Ancient prokaryotes with unique cell walls enabling survival in extreme environments.

Halophiles

Salt-loving archaebacteria inhabiting highly saline habitats.

Thermoacidophiles

Heat- and acid-tolerant archaebacteria found in hot, acidic environments.

Methanogens

Archaebacteria that produce methane; reside in anaerobic habitats such as ruminant guts.

Eubacteria

‘True’ bacteria with rigid cell walls and, if motile, a flagellum.

Cyanobacteria

Photosynthetic, chlorophyll-a containing eubacteria also called blue-green algae.

Heterocyst

Thick-walled cyanobacterial cell specialised for atmospheric nitrogen fixation.

Chemosynthetic bacteria