A random mutation gives one plant in a population of annual wildflowers an allele that causes earlier flowering. The mutation occurs before a change to shorter growing seasons. Plants that flower before the season ends are more likely to produce seeds. Which statement identifies evidence that natural selection, rather than the original mutation alone, has changed the population?
The early-flowering allele is found in one plant before the first shorter growing season.
New mutations producing the early-flowering allele occur more often as the growing seasons become shorter.
Plants flower earlier in shorter growing seasons whether or not they carry the early-flowering allele.
The early-flowering allele is found in an increasing proportion of the plants over several generations.
85 exam-style questions on Edexcel GCSE Biology 4.1 Evolution and natural selection, covering 4.1.1 Work of Darwin and Wallace and 4.1.2 Resistant organisms and evolution. Each one has a worked solution and a mark scheme showing where the marks go.