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Unit 4
Biodiversity and natural resources


A species is:

A species is a group of organisms with similar morphology, physiology and behaviour,
which can interbreed to produce fertile off spring, and which are reproductively isolated
(in place, time or behaviour) from other species.

Habitat and community:

A habitat can…

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Adapted to their environment:

Features which enable organisms to survive are called adaptations. Adaptations can be classified
as one of the three below and can sometimes overlap:

1. Behavioural adaptations behavioural adaptations are any actions by organisms which
help them to survive or reproduce e.g. plants moving their leaves towards…

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Evolution by natural selection:

Evolution is more precisely defined as `a change in allele frequency in a population over
time (generations)'.
An allele can be selectively neutral (has no advantage or disadvantage) but suddenly
become selectively very advantageous when the environment changes.
The fundamentals of the theory are summarised in…

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`Biodiversity' is a shortened form of the words `biological diversity'. Biodiversity is used in
everyday language to mean the variety of life, and in particular the wealth of different
species that exists as a result of natural selection.
In biological terms it refers to the variety of species that…

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A hierarchical system:

Placing organisms into groups based on shred features, known as classification or
taxonomy , results in a manageable number of categories and has been the principal aim
of all classification systems.
A taxonomic hierarchy is created. This is a series of nested groups or taxa (singular taxon),…

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Biodiversity within a species:

Individuals within a species differ from one another and show variation.
This genetic diversity, and the greater the variety of genotypes the more genetically
diverse the population. Genetic diversity allows the population to adapt to changing
conditions so should be conserved.

Sources of genetic variation:

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Genetic diversity may be visible:

Sometimes genetic differences within a species show up clearly in the external
Much genetic variation has no visible effect on phenotype. It is made up of molecular
differences which can only be detected using techniques such as gel electrophoresis or
proteins; two alleles at…

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Endemic species:

An endemic species is one whose habitat is restricted to a particular area. The term could
refer to an animal, a plant, a fungus, or even a microorganism.
Endemic species are often endangered, and particular examples may become a focus
point for campaigns to protect biodiversity in a…


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