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4.3 Classification and Evolution

Biological Classification
Binomial system ­ a system that uses the genus name and the species name to avoid confusion
when naming organism
Classification ­ the process of placing living things into groups
Reasons for classification:

For convenience
To make the study of living things easier

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Species ­ a group of organisms that can freely interbreed to produce fertile offspring
This definition does not work for organisms that reproduce asexually and is very hard to apply to
organisms known only from fossil records and the like.

Phylogenetic definition of species ­ a group of individual organisms…

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< 5um Diffusion Saprophytic ­ Autotrophi Heterotrophi
of live on dead/ c ­ makes c ­ both
Diffusion of nutrients decomposing own food makes own
nutrients matter food and
eats other

Evidence used in Classification

Biological Molecules
Some biological molecules, such as those for DNA replication and respiration are…

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3. Immunological Comparisons
Similar proteins will bind to the same antibodies. So, if antibodies to a human version
of a protein were added to isolated samples from other species, then any protein
similar to the human version will be recognised and bind to the antibody.

Artificial Classification ­ classification for…

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Divergent evolution is where another species has evolved from the original common ancestor and
the two species get progressively less similar.
Convergent evolution is where two species, who may share the same environment and therefore
the same factors that affect survival, evolve similar characteristics.
Natural Selection

Natural Selection ­ the…

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Variation ­ the presence of variety the differences between individuals
Intraspecific variation ­ variation between members of the same species

Interspecific variation ­ the differences between species
Continuous variation ­ variation where there are two extremes and a full range of values in

Discontinuous variation ­ variation where…

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5. Student's ttest ­ used to compare two means


Adaptation ­ a characteristic that enhances survival in the habitat

Anatomical adaptations ­ structural features
Behavioural adaptations ­ the ways that behaviour is modified for survival

Physiological adaptations ­ affect the way that processes work (also called biochemical)
Marram Grass…

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5. Therefore they pass on their advantageous characteristics (inheritance)
6. The next generation will have a higher proportion of individuals with the successful
characteristics. Over time, the group of organisms becomes well adapted to their

Pesticide Resistance in insects
An insecticide applies a very strong selection pressure. If the…


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