(a) The sea blush, Plectritis congesta, is a flowering plant that grows on the west coast of North America. Individual sea blush plants produce fruit that is either winged or wingless. Investigations have shown that this characteristic is controlled by a single gene with two alleles: • a dominant winged fruit allele • a recessive wingless fruit allele. Fig. 3.1 shows the difference in structure between winged fruit and wingless fruit phenotypes. [Figure 3.1]

1. (a)(i)A large sample of sea blush fruits was collected and their fruit-wing characteristic was recorded. Name the type of variation that is shown for the fruit-wing characteristic of the sea blush.[1]
2. (a)(ii)Different sea blush plants can have fruit with different colours. Suggest two ways in which a new fruit colour could naturally occur in a sea blush population.[2]
3. (a)(iii)Early taxonomists classified sea blush plants with winged fruits as a different species to sea blush plants with wingless fruits. Since this time, evidence from observations and experiments has confirmed that the plants belong to the same species. Suggest three examples of the evidence obtained that helped to confirm that these sea blush plants belong to the same species.[3]
4. (b)Natural selection occurs in populations, such as in populations of sea blush plants. Explain why natural selection occurs in populations.[5]

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