Question

A homozygote recessive parent (rrgg) is crossed with a heterozygotes parent (R__ G__). R is dominant for rough while r is recessive for smooth and G is dominant for green while g is recessive orange.

The offspring from this cross are:
- Rough, orange = 43
- Smooth, green = 47
- Rough, green = 3
- Smooth, orange = 7
What is the configuration of the alleles in the heterozygous parent?

Answer 1

The heterozygous parent's genotype in the dihybrid cross is RrGg, suggested by the 1:1 ratio of offspring phenotypes for both seed color and texture, with green coloration and rough texture being dominant traits.

Step-by-step explanation:

The question is determining the genotype of the heterozygous parent in a dihybrid cross involving traits for seed texture and color in pea plants. The homozygous recessive parent has the genotype rrgg, and the offspring phenotypes give clues about the alleles of the heterozygous parent. Since dominance and recessive patterns result in a 3:1 ratio in monohybrid crosses, and a 9:3:3:1 ratio in dihybrid crosses due to independent assortment, we can infer the genotype of the second parent from the offspring phenotypes.

The offspring phenotypes include a 1:1 ratio of green (dominant) to orange (recessive) color, which suggests a heterozygous trait for color, Gg. Similarly, the texture ratio is not a 3:1, but if it were a large enough sample size, we would expect this ratio for texture as well, which suggests a heterozygous trait for texture, Rr. However, the exact ratio deviates from 3:1, probably due to the small sample size. Considering the provided data, the genotype of the heterozygous parent for these two traits can be assumed as RrGg.