0610_s11_qp_32
A paper of Biology, 0610
Questions:
6
Year:
2011
Paper:
3
Variant:
2

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For Examiner's Use The four o’clock plant, Mirabilis jalapa, can have flowers of three different colours as shown in . yellow flower crimson flower orange-red flower A student crossed some crimson-flowered plants with some yellow-flowered plants (cross 1). She collected the seeds and grew them. All of the plants that grew from these seeds had orange-red flowers. Complete the genetic diagram to explain the result of cross 1. parental phenotypes parental genotypes gametes offspring genotype offspring phenotype crimson flowers ACAC × × + yellow flowers AYAY For Examiner's Use The student then carried out three further crosses as shown in Table 4.1. Table 4.1 cross genotypes of offspring 2 offspring of cross 1 × offspring of cross 3 offspring of cross 1 × crimson-flowered plant 4 offspring of cross 1 × yellow-flowered plant Complete Table 4.1 by writing the genotypes of the offspring of crosses 2, 3 and 4, using the same symbols as in the genetic diagram in . Write the genotypes in Table 4.1. You may use the space below for any working. Flower colour in M. jalapa is not an example of the inheritance of dominant and recessive alleles. Explain how the results of the crosses show that these alleles for flower colour are not dominant or recessive. For Examiner's Use Flowers from M. jalapa were cross-pollinated. Explain the difference between self-pollination and cross-pollination. Some species of plants are self-pollinated. Discuss the long-term effects of self-pollination on the evolution of these plants.
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