Flower color in snapdragons results from the amount of the pigment anthocyanin i
ID: 163351 • Letter: F
Question
Flower color in snapdragons results from the amount of the pigment anthocyanin in the petals. Red flowers are produced by plants that have full anthocyanin production, and ivory-colored flowers are produced by plants that lack the ability to produce anthocyanin. The allele An1 has full activity in anthocyanin production, and the allele An2 is a null allele. Pure-breeding red snapdragons are crossed to pure-breeding ivory snapdragons and 100% of the F1 offspring are pink. if this outcome is the result of incomplete dominance what genotypic AND phenotypic ratios will be observed in the F2 generation?
Explanation / Answer
F2 generation for self pollinated F1 flowers:
With incomplete dominance we get a blending of the dominant & recessive traits so that the third phenotype is something in the middle (red x white = pink).
Phenotypic Ratio: 1 (RED) : 2 (PINK) : 1 (WHITE) .
Genotypic Ratio : 1 (Homozygous dominant) :2 (Heterozygous Incomplete Dominant) :1 (Homozygous recessive)
F2 generation when cross is between F1 pink flower and pure breeding Red:
When the F1 (first filial) generation is allowed to cross-pollinate with true breedingred plants, the resulting plants (F2 generation) consist of red and pink phenotypes.
Phenotypic Ratio : 1 (RED) :1 (PINK).
Genotypic ratio : 1 (Homozygous Dominant) : 1 (Heterozygous Incomplete Dominant).
F2 generation when cross is between F1 pink flower and pure breeding White:
When the F1 (first filial) generation is allowed to cross-pollinate with true breedingwhite plants, the resulting plants (F2 generation) consist of white and pink phenotypes.
Phenotypic Ratio : 1 (WHITE) :1 (PINK).
Genotypic ratio : 1 (Homozygous Recessive) : 1 (Heterozygous Incomplete Dominant).
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