Gene mutations occur spontaneously; the mutation rate is increased by mutagenic agents
Gene mutations can happen by chance at any time. Certain environmental factors, called mutagenic agents, make mutations happen more often.
Real World
After the Chernobyl nuclear disaster in 1986, ionising radiation acted as a mutagen, significantly increasing mutation rates in surrounding populations of barn swallows and Scots pine trees.
Exam Focus
Distinguish spontaneous mutations (random replication errors) from induced mutations (caused by named mutagens like UV or benzene).
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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