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Early classification
2000 years ago, Aristotle divided all living thing into two
large groups
Plantae and Animalia
 Most animals are motile (move) in order to obtain
food
 Most plants are stationary and obtain food through
photosynthesis
Micro-organisms
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The invention of the microscope in the 1600s made classification
more difficult
Many micro-organisms had characteristics of both plants and
animals
euglena:
has flagellum to propel itself – animal characteristic
goes through photosynthesis – plant characteristic
Micro-organisms - Protista
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Protista - Ernst Haeckel (1866) came up with the 3-rd kingdom ]
Protista was the kingdom for micro-organisms that were
neither plants nor animals
Extremely diverse kingdom (size, habitat, behaviour)
Micro-organisms - Fungi
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Fungi (mushrooms, mould) were originally in the plant kingdom
Fungi are sessile (stationary) and many grow in the ground – plants?
No!
Fungi are not photosynthetic
Different methods of reproducing
Micro-organisms - Bacteria
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Bacteria are single celled organisms
Bacteria lack membrane-bond organelles
They are the smallest organisms on Earth
Thy are most dominant form of life in every habitat
Micro-organisms - Archea
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1990 – Bacteria Kingdom was split into Bacteria and Archaea
Archaea cell membranes and walls have a unique chemical makeup
(resistant to physical and chemical disruptions)
Many inhabit extreme environments (salty, hot, cold, low-oxygen)
classification