Question

The genotype of green seed pod is denoted as GG and yellow seed pod as gg.
a) State the seed pod color you would expect in their F1 progeny.
b) With the help of cross, explain the fraction of green and yellow seed pods in F2 generation.
c) State the expected ratio of genotypes Gg and gg.

Answer 1

Mendel’s Dihybrid cross explains the reappearance of the trait that didn’t appear in F1 generation. It explains that when a recessive trait is present in homozygous condition, it will be expressed in the progeny. Mendel performed his experiments on a pea seed and the traits that he considered were seed color and seed shape for this experiment.

Complete answer:
a) When GG and gg traits are crossed to produce F1 generation, all four progeny will have Gg genotype and the seed pod color will be Green in color as the green color seed pods is dominant. In a heterozygous condition, the dominant phenotype is expressed over the recessive one.
b) For F2 generation, the cross occurs between Gg and Gg genotypes. After crossing, the genotypes of progeny will be GG, Gg, gG, and gg. So, out of these four progenies, three of them would have green seed pod, i.e. 3/4th of the progeny, while one of them, gg, would have yellow seed pod because of recessive homozygous genotype. That is 1/4th of the progeny.
c) From the above cross, the ratio of Gg will be 2/4 and that of gg will be ¼.

Note:
The Law of Independent Assortment states that “ when two pairs of traits are combined in a hybrid, segregation of one pair of traits is independent of the other pair of traits.” Accordingly, the gametes must carry all possible combinations of the factors in equal frequency.