0610_w17_qp_42
A paper of Biology, 0610
Questions:
6
Year:
2017
Paper:
4
Variant:
2

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The garden pea, Pisum sativum, is a plant which has flowers that have both male and female parts. P. sativum is naturally self-pollinating. Discuss the advantages and disadvantages of self-pollination. Gregor Mendel studied inheritance in the garden pea, P. sativum. The flowers of P. sativum that he studied were either purple or white. The gene that controls flower colour has two alleles, B and b. When Mendel crossed purple-flowered plants with white-flowered plants all the plants in the next generation had purple flowers. Table 4.1 shows five genetic terms that can be applied to Mendel’s study of the inheritance of flower colour. Complete Table 4.1 by stating an example of each genetic term. The first one has been completed for you. Table 4.1 term example in P. sativum dominant trait purple flowers recessive allele phenotype homozygous genotype heterozygous genotype Test crosses can be used to determine the genotype of a plant with purple flowers. The genetic diagrams show test crosses for purple-flowered plants with two different genotypes. Complete the genetic diagrams for test cross 1 and test cross 2. test cross 1 parental phenotype purple flowers × white flowers parental genotype Bb × genotypes of gametes + offspring genotypes offspring phenotypes test cross 2 purple flowers × white flowers BB × + Pickerel weed, Pontederia cordata, is a plant that grows in shallow water on the edges of ponds and lakes in North America. A few seedlings of these plants are white. The white seedlings cannot make chlorophyll. Researchers carried out several crosses using pickerel weed plants. Their results are shown in Table 4.2. Table 4.2 cross number of offspring green white Select suitable symbols for the alleles and state the possible genotypes of the parents for each cross. cross 1 cross 2 It is not possible to carry out a test cross with pickerel weed plants. Suggest why.
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