Monday 5th November Section 2
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November 5, 2012, 1:31 pm
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Classification
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KEGS Biology Blog 
Classification: The process of sorting living things into groups based on their similarities and/or differences. It reflects evolutionary relationships
Why do we classify organisms?
-Scientific research
-To help identify organisms
-To help us to see the relationships between organisms
-For our own convenience
Taxonomy: The study of the principles of classification, i.e. the differences and similarities between organisms
For example, an organism’s;
-habitat
-nutrition
-behaviour
-anatomy (how its body is made up)
-physiology (how its body functions)
-biochemistry
-how it reproduces
Phylogeny: The study of the evolutionary relationships between organisms
On an evolutionary tree, the closer the organisms are, the more closely related they are, therefore the more recently they shared a common ancestor.
Carl Linnaeus came up with a classification system involving 5 ranked categories; kingdom, class,order, genus, species
However this was not good enough, with more subdivisions required. Organisms such as kangaroos and ducks ended up being shown to be closely related, which they clearly weren’t based upon their physical appearance alone
This system was developed by Richard Whittaker. He created 5 kingdoms, meaning there were far more subdivisions, enabling more accurate classification of organisms
Each kingdom was also more detailed containing;
Kingdom, Phylum, Class, Order, Family, Genus, Species
(King penguins climb over frozen grassy slopes)
Classification of humans:
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidee
Genus: Homo
Species: Sapiens
All members of the same species are more or less the same with little variation. Humans for example, despite being slightly different in appearance, are by-in-large the same when compared with different species.
As you move up the ranks, there is more diversity.
An alternative method of classification is the 3 domains, splitting all organisms into bacteria, archaea and eukaryotae, before then using the other subdivisions.
Comment by jakepalmer1 November 8, 2012 @ 6:16 pm