Question

) When predicting the phenotype of the offspring from a dihybrid cross, why is it so important that each gene is located in a different chromosome? B) You crossed a tall plant that also produces purple flowers with a short plant that produces purple flowers. Assume tall and purple flower are dominant traits. The offspring were: 100% tall plants, ¾ of the plants produced purple flowers and the remaining 1/4 of the plants produced white flowers. What were the possible genotypes of the parents?

Answer 1

Answer:

a) The genes present on separate chromosomes exhibit indepedent assortment.

b) The genotype of tall and purple flower parent= TTPp

The genotype of short and purple flower parent: ttPp

Explanation:

a) In a dihybrid cross, if the genes are present on the same chromosome, they will not exhibit independent assortment. The genes present on the same chromosome are called linked genes. Linked genes are inherited together. The absence of independent assortment of a linked gene gives more of parental types in F2 progeny. Therefore, if genes are not present on a separate chromosome, Mendel’s ratios deviate.

b) Alleles for tallness and purple flower are dominant. In the progeny, all the plants are tall. This means that the dominant tall plant is homozygous. With respect to flower color, the trait exhibits segregation of dominant and recessive alleles and both purple and white flower progeny are obtained. This makes both the plants heterozygous for the flower color gene.  

The genotype of tall and purple flower parent= TTPp

The genotype of short and purple flower parent: ttPp