Identify and describe What Is Variation?, Genetic and Environmental Causes and Mutations and Genetic Variation in the context of variation.
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GCSE Biology Revision
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GCSE Biology revision
Variation
Variation and evolution
Your specification
AQA student objectives
Learning pathway
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Explain the relationships between What Is Variation?, Genetic and Environmental Causes and Mutations and Genetic Variation and how they contribute to variation.
Apply and analyse knowledge of What Is Variation?, Genetic and Environmental Causes and Mutations and Genetic Variation to interpret unfamiliar information about variation.
Revision summary
Key knowledge
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What Is Variation?
- Variation refers to all the differences in characteristics between individuals within a population.
- There are three main causes of variation: genetic, environmental, and a combination of both.
Genetic and Environmental Causes
- Genetic variation is caused by the alleles individuals inherit, with examples including hair colour and eye colour.
- Environmental variation occurs when characteristics are influenced by surroundings, such as language spoken or flower colour depending on soil pH.
- Some characteristics, like height in humans, result from a combination of genes and the environment, requiring both the right alleles and a suitable diet.
Mutations and Genetic Variation
- All genetic variation within a species ultimately arises from mutations, which are random changes to DNA.
- Most mutations have no effect on the phenotype, but some can influence it, and a small number actually determine it.
Beneficial Mutations and New Phenotypes
- Rarely, a mutation can produce a new phenotype that becomes beneficial if the environment changes.
- An example is the UK rabbit population in the 1950s, where a mutation gave some rabbits resistance to a deadly virus, and this beneficial phenotype became widespread.