Biology unit 2: Causes of variation

Genetic and environmental factors

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  • Created by: Samm
  • Created on: 21-04-12 20:26

Variation exists between all individuals

Two types of variation..

Intraspecific - differences that occur within a species.

Interspecific - variation between different species.

a way to remember the difference.. int-er-specific means diff-er-ent species!

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Genetic factors

All members of a species have the same genes.

However, individuals within that species may have different versions of the genes - alleles.

alleles make up an organisms genotype.

different genotypes result in variation in phenotype - the characteristics being displayed.

You inherit genes from your parents, so genetic variation is inherited.

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Environmental factors

The appearance (phenotype) of an individual is also affected by the environment.. e.g.

Plant growth - affected by the amount of minerals available in soil.

Fur colour - affected by the temperature of an animals habitat.

Identical twins - may be affected by different illnesses or growing up in different areas.

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It's a combination

Variation is often a combination of genetic and environmental factors.. e.g.

A person may have the genes to grow six foot tall, but whether they do will depend on environmental factors such as diet and health.

Good luck on your exams!

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