Cross a heterozygous axial, hybrid round seed plant with a hybrid axial, heterozygous round seed plant. Only list the phenotypic ratio at the end.

The phenotypic ratio is 9:3:3:1

Explanation:

We need to cross a heterozygous axial, hybrid round seed plant with a hybrid axial, heterozygous round seed plant. When referring to a hybrid plant for a trait, we are meaning that the plant is heterozygous for that trait.

Let us assume that round is the dominant trait, codified by a diallelic gene, so

Let us also assume that axial is the dominant trait, so

Cross:

Parentals)   RrAa  x  RrAa

Gametes)  RA, Ra, rA, ra

                 RA, Ra, rA, ra

Punnett Square)     RA           Ra          rA          ra

                   RA      RRAA    RRAa      RrAA     RrAa

                   Ra      RRAa     RRaa       RrAa     Rraa

                   rA       RrAA     RrAa       rrAA      rrAa

                   ra       RrAa      Rraa        rrAa       rraa

F1) Among the progeny, we expect to observe the following phenotypic ratio:

the correct answer is b