House finches are small birds commonly found in North America.
Many people living in urban areas feed birds using feeders containing large, hard sunflower seeds. Scientists have found that house finches in urban areas have, on average, deeper (thicker) beaks than house finches living in nearby wild forest areas where bird feeders are not present.
Use Charles Darwin's theory of natural selection to explain why the house finches in urban areas have deeper beaks than those in wild forest areas.
122 exam-style questions on OCR GCSE Biology 5.2 Natural selection and evolution, covering 5.2.1 Genetic variation within a population, 5.2.2 Developments in classification systems, 5.2.3 How evolution occurs through natural selection, 5.2.4 Evolution as change over time, 5.2.5 Evidence for evolution, and 5.2.6 Darwin and Wallace. Each one has a worked solution and a mark scheme showing where the marks go.