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| Dihybrid Inheritance |
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| It is a cross involving two pairs of contrasting characters. For this experiments on dihybrid inheritance. Mendel selected the contrasting characters in the seed coat and cotyledons. He conducted a cross pollination between a pure breeding plant with round seed coat and yellow coloured cotyledons and a pure breeding plant with wrinkled seed coat and green coloured cotyledons. In the F1 generation, all the resulting plants had round seed coat and yellow coloured cotyledons. |
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| When he allowed these F1 plants to undergo self pollination, in the F2 generation, four types of plants were obtained with round yellow, round green, wrinkled yellow and wrinkled green seeds in the ratio of 9:3:3:1. |
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| fig. 18.10 Dihybrid Inheritence |
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| Based on these results, Mendel proposed the law of independent assortment or second law of inheritance. The law is stated as follows 'In a dihybrid cross, the factors responsible for the two pairs of contrasting characters stay together in the F1 generation, but assort independently during the formation of gametes'. |
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