Question

In a cross between two strains that are true breeding for purple and white flowers, the F₂ phenotypic ratio would be ¼ purple, ¼ white, and ½ lavender if the flower color phenotype exhibits incomplete dominance. True / False.

Answer 1

True

Step-by-step explanation:

This is a cross involving a single gene coding for flower colour. According to the question, the purple allele (P)!exhibits an incomplete dominance over the white allele (p) i.e. it (purple allele) is unable to mask its (white allele) expression in the F1 hybrid, instead a third phenotype (lavender, Rr) is formed, which is an intermediate phenotype of both purple and white Phenotypes.

Since both parents are truebreeding/homozygous, they will form heterozygous F1 offsprings with lavender flower colour. If this F1 offsprings are self-crossed, four possible offsprings will be produced, where 1 will have a purple phenotype (RR), 2 will have a lavender phenotype (Rr) and 1 will have a white phenotype (rr).

Hence, the phenotypic ratio of this cross portraying incomplete dominance will be 1/4 purple, 1/2 or 2/4 lavender and 1/4 white.