Question

The gene for flower position in pea plants exists as axial or terminal alleles. Given that axial is dominant to terminal, list all of the possible F1 and F2 genotypes and phenotypes from a cross involving parents that are homozygous for each trait. Express genotypes with conventional genetic abbreviations.

Answer 1

Answer:

F1

A A

a Aa Aa

a Aa Aa

All the offspring have flower located at axial position

F2

A a

A AA Aa

a Aa aa

Three offspring with genotype i,e Aa, Aa and Aa will have flower located at axial position

Only offspring with genotype "aa" will have flower located at terminal position

Explanation:

Let the allele "A" represent the characteristics of axial position of flower

Let the allele "a" represent the characteristics of terminal position of flower

Given -

"A" is dominant over "a"

F1 generation -

Two parents with homozygous genotype for both A and a are crossed . The punnet square for the cross between "AA" and "aa" is as follows -

A A

a Aa Aa

a Aa Aa

Thus the genotype of offspring is "Aa"

Since, "A" is dominant over "a", all the offspring have flower located at axial position

F2 generation-

The cross between two parents having heterozygous genotype "Aa" will take place .

The punnet square for the cross between "Aa" and "Aa" is as follows -

A a

A AA Aa

a Aa aa

Three offspring with genotype i,e Aa, Aa and Aa will have flower located at axial position

Only offspring with genotype "aa" will have flower located at terminal position