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Define classification.

Classification is the organisation of living organisms into groups. This process is not random but is based on a number of accepted principles.


Members of a single species are similar to one another but different from members of other species...

They have similar genes and therefore resemble one another physically and biochemically.
They have similar patterns of development and similar immunological features.
They occupy the same ecological niche.


Members of a single species are capable of breeding...

To produce fertile offspring so that they are able to successfully produce more offspring.
The genes of each member of the species all belong to the same gene pool.


Which Swedish scientist devised a common system of naming organisms?



What is Linnaeus' system called?

The binomial system


Give three feature of the binomial system.

It is based upon Latin or Greek names
The first name, called the generic name, denotes the genus to which the organism belongs.
The second name, called the specific name, denotes the species to which the organism belongs .


What are the rules of the binomial system?

The names are printed in italics or underlined.
The first letter of the generic name is in upper case but the specific name is in lower case.
If the specific name is not known it can be written as sp. (not in italics).


The grouping of organisms is known as...



What is taxonomy?

The theory and practice of biological classification.


What are the two main forms of biological classification?

Artificial classification
Natural classification


Describe artificial classification

Artificial classification divides organisms according to differences that are useful at the time. Such features may include colour, size, number of legs, leaf shape etc.

(These are analogous characteristics where they have the same function but do not have the same evolutionary origins. E.g wings of butterflies and birds.)


Describe natural classification.

a) is based upon the evolutionary relationships between organisms and their ancestors.
b) classifies species into groups using shared features derived from their ancestors.
c) arranges the groups into a hierarchy, in which the groups are contained within larger composite groups with no overlap.

(These are homologous characteristics as they have similar evolutionary origins regardless of their functions.)


Give the order of taxonomic ranks:

King Prawn Curry Or Fat Greasy Sausages:


What is phylogeny?

The evolutionary relationship between organisms.


In phylogeny what is represented by a tree-like diagram called a...

Phylogenetic tree?

The phylogenetic relationships or different species.
In these diagrams, the oldest species is at the base of the tree while the most recent ones are represented by the ends of the branches.


Give some difficulties with defining species.

-Species are not fixed forever, but change and evolve over time.
- There can be considerable variation within species among individuals.
- Many species are extinct and have left no fossil record.
- Some species rarely, if ever, reproduce sexually.
- Members of different groups of the same species may be isolated e.g by oceans and so never meet and never interbreed.
- Some species are sterile. E.g mules.


Why are mules infertile?

Horses and donkeys have a different number of chromosomes. Meiosis cannot take place in mules so they produce no gametes.