biology
Incomplete/Codominance Problem
In snapdragons the dominant allele "R" produces red flowers and its recessive form, "r" produces white flowers. Normally what would you expect for the F1 genotype and phenotype ratios if a homozygous red flower and a homozygous white flower are crossbred?
When the above cross is done the F1 generation is all pink flowers. What pattern of inheritance is illustrated by snapdragons? What are the F2 genotypic and phenotypic ratios if the F1 flowers are crossbred among themselves?
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Answers
The pattern of inheritance illustrated by snapdragons is codominance. In codominance, both dominant alleles are expressed fully in the phenotype of the offspring. In this case, both the "R" allele and the "r" allele are expressed, leading to pink flowers. When the F1 flowers are crossbred among themselves, the F2 generation will have a 1:2:1 genotypic ratio of RR:Rr:rr. This equates to a 1:2:1 phenotypic ratio of red:pink:white.
