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B6 N) Classification
B6 N) Classification
We use classification systems to organise living organisms into groups. Overtime classification systems have changed as we have gained a better understanding as to what happens in living organisms – we will look at why classification systems have changed overtime in a little bit more detail later.
Linnaeus System
The first classification system was developed in the 1700s by Carl Linnaeus. He classified organisms based on their structure and characteristics. In the Linnaeus system, organisms are classified into a kingdom, a phylum, a class, an order, a family, a genus and a species.
The first classification system was developed in the 1700s by Carl Linnaeus. He classified organisms based on their structure and characteristics. In the Linnaeus system, organisms are classified into a kingdom, a phylum, a class, an order, a family, a genus and a species.
We can remember the order of these different subdivisions by remembering; Kids Prefer Candy Over Fresh Green Salad (kingdom, phylum, class, order, family, genus and species).
Let’s have an example of a tiger being classified.
Organisms are then named using Latin by the binomial system of genus and species. Humans are homo sapiens; the “homo” is our genus and the “sapiens” is the species.
Let’s have an example of a tiger being classified.
- kingdom - animal
- phylum - vertebrate
- class - mammal
- order - carnivorous
- family - cat
- genus - big cat
- species - tiger
Organisms are then named using Latin by the binomial system of genus and species. Humans are homo sapiens; the “homo” is our genus and the “sapiens” is the species.
Changes to the Classification System
The Linnaeus classification system relied solely on human judgment to classify organisms. Overtime technology has advanced, which has meant that we can understand organisms and their internal structures in more detail. This is because we can now use microscopes, biochemistry and DNA to help us classify organisms as accurately as possible.
In 1990, Carl Woese developed a new “three-domain system”. This new system came about because of new chemical analysis techniques, which found that some organisms that were closely related in the old classification system are actually further apart than was first thought. In Carl Woese “three-domain system” the organisms are first split into three domains (large groups). These three domains are:
Each of these domains are then subdivided into kingdom, phylum, class, order, family, genus and species.
The Linnaeus classification system relied solely on human judgment to classify organisms. Overtime technology has advanced, which has meant that we can understand organisms and their internal structures in more detail. This is because we can now use microscopes, biochemistry and DNA to help us classify organisms as accurately as possible.
In 1990, Carl Woese developed a new “three-domain system”. This new system came about because of new chemical analysis techniques, which found that some organisms that were closely related in the old classification system are actually further apart than was first thought. In Carl Woese “three-domain system” the organisms are first split into three domains (large groups). These three domains are:
- Archaea – these are primitive bacteria that usually live in extreme envioronments like very salty lakes, inside volcanoes or at the bottom of oceans.
- Bacteria – these are known as true bacteria. They look very similar to the archaea but there are quite a few biochemical differences.
- Eukaryotes – this domain includes animals, plants, fungi and protists. Homo sapiens (humans) are found in this domain.
Each of these domains are then subdivided into kingdom, phylum, class, order, family, genus and species.
Evolutionary Trees
Evolutionary trees show how organisms are related to each other. Scientists use current classification data for living organisms (such as DNA analysis and biochemical processes) and fossil data for extinct organisms (extinct organisms are organisms that are no longer around). An example of an evolutionary tree is shown below.
Evolutionary trees show how organisms are related to each other. Scientists use current classification data for living organisms (such as DNA analysis and biochemical processes) and fossil data for extinct organisms (extinct organisms are organisms that are no longer around). An example of an evolutionary tree is shown below.
The tips of the trees represent different species; the different species for the above evolutionary tree are chimpanzees, humans, gorillas and orangutans. The joining of two branches represents common ancestors. The closer the common ancestors are, the more closely related the two species are. For the above evolutionary tree, chimpanzees and humans have a closer common ancestor than chimpanzees and orangutans. Therefore, chimpanzees and humans are likely to have more shared characteristics compared to the shared characteristics between chimpanzees and orangutans.