Question

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

Answer 1

The phenotypic ratio is 9:3:3:1

• 9/16 individuals with axial flowers and rounded fruits, R-A-
• 3/16 individuals with terminal flowers and rounded seeds, R-aa
• 3/16 individuals with axial flowers and wrinkled seeds, rrA-
• 1/16 individuals with terminal flowers and wrinkled seeds, rraa

Step-by-step 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

• R is the dominant allele
• r is the recessive allele

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

• A is the dominant allele
• a is the recessive allele

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:

• 9/16 individuals with axial flowers and rounded fruits, R-A-
• 3/16 individuals with terminal flowers and rounded seeds, R-aa
• 3/16 individuals with axial flowers and wrinkled seeds, rrA-
• 1/16 individuals with terminal flowers and wrinkled seeds, rraa