Question

A genetic cross between a plant that produces purple flowers and a plant that produces yellow flowers was performed. All of the resulting offspring produced yellow flowers. The gene for flower coloration is “B”. What is the dominant color and what must the different genotypes of the parents and their offspring be?

Answer 1

The gene for flower coloration is B.

Let, B be the dominant allele for yellow flower

and b be the recessive allele for purple flower.

Yellow flowered plant x Purple flowered plant

BB x bb

gametes B b

offsprings Bb (all yellow flowered plants).

B and b form Bb that is the yellow flowered offsprings.

Here Yellow is the dominant color as BB and Bb both genotypes show phenotype of yellow flowering plant, as only dominant allele is expressed in both homozygous and heterozygous condition.

Genotype of Yellow flowering parent plant is BB

Genotype of Purple flowering parent plant is bb

Genotype of Yellow flowering offspring plant is Bb.