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Question : What is incomplete dominance? Explain inheritance of flower colour in snapdragon |
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Answer» Solution :"When the alleles are in HETEROZYGOUS condition, the dominant gene fails to suppress the recessive gene completely and produce a new trait which is DIFFERENT from their parents". The phenotype of `F_1` generation does not resemble either of the two parents and the expression is in between the two. Inheritance of flower colour in the dog flower or snapdragon (Antirrhinum sps.) is a good example for incomplete DOMINANCE. In a cross between true breeding red flowered (RR) plant and true breeding WHITE flowered (rr) plants, the `F_1` hybrids produce pink coloured flowers (Rr). When the `F_1` hybrids are self pollinated (self cross), the `F_2` generation resulted in the ratio of 1:2:1[1Red (RR) : 2 Pink (Rr): 1White (rr)]. Here, the phenotype ratio does not resemble the Mendelian monohybrid cross but the genotype ratio is EXACTLY similar to that of Mendelian monohybrid cross. 
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