Individuals within a population may show a wide range of variation in phenotype due to genetic and environmental factors; the primary source of genetic variation is mutation
Individuals in a population look and function differently from one another — this is phenotypic variation. Genes and the environment both cause it, but mutation is the original source of all genetic differences.
Real World
Identical twins raised apart often differ in body mass and skin tone — their shared DNA is identical, but different diets, sun exposure, and exercise habits produce distinct phenotypes, showing how environment layers onto genetic variation.
Exam Focus
Distinguish genetic from environmental variation with named examples; examiners expect you to identify mutation as the ultimate source.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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