Question

A cross was made between a plant that has blue flowers and purple seeds to a plant with white flowers and green seeds. This is a parental cross and the parents are homozygous for both characters (color of the flower and color of the seeds). The resulting offspring (the F1 generation) is allowed to self-fertilize. Complete a Punnett square representing the F2 generation that results from the above self-fertilization. The traits blue flowers (B) and purple seeds (P) are dominant to white flowers (b) and green seeds (p).Complete the Punnett square by hand, and provide the phenotypic ratio of the F2 generation.

Answer 1

Answer- A cross was made between a plant that has blue flowers and purple seeds to a plant with white flowers and green seeds.  The traits blue flowers (B) and purple seeds (P) are completely dominant to white flowers (b) and green seeds (p).

• For expression of dominant character, only one dominant allele is sufficient to provide the dominant phenotype while for recessive character both the copies of recessive allele is necessary to provide the recessive phenotype. We will use this point to determine the phenotye ofoffsprings of F1 and F2 generation.
• The parents are homozygous for both characters (color of the flower and color of the seeds) and the cross was made between a plant that has blue flowers(B) and purple seeds(P) to a plant with white flowers(b) and green seeds(p) and F1 generation was produced which was then self-fertilize and F2 generation was produced. It is a dihybrid cross. In a dihybrid cross, we will take two characters for a plant and make a cross between parents having dominant character with parents having recessive character and make punette square. Punette square is the graphical representation of all the possible genotypes of a genetic cross to determine the genotypic(number of genotypes) and phenotypic( external appearance)ratio of the cross.

Cross and genotypic and phenotypic ratio is given in the image attached.