Question

In chickens, comb shape is determined by alleles at two loci (R, r and P, p). A walnut comb is produced when at least one dominant allele R is present at one locus and at least one dominant allele P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive alleles are present at the first locus and at least one dominant allele is present at the second (genotype rr P_). If two recessive alleles are present at the first and at the second locus (rr pp), a single comb is produced. Progeny with what types of combs and in what proportions will result from the following crosses?
a. RR PP × rr pp
b. Rr Pp × rr pp
c. Rr Pp × Rr Pp
d. Rr pp × Rr pp
e. Rr pp × rr Pp
f. Rr pp × rr pp

Answer 1

Answer:

a) All Walnut , Genotype - RrPp

b) Walnut : Rose: Single

1:1:2

Explanation:

Phenotype and their Genotype -

Walnut comb - R_ P_

Rose Comb - R_ pp

Pea Comb - rr P_

Single Comb  - rr pp

a) RR PP *  rr pp

All progenies will have genotype RrPp (Walnut Comb)

b) Rr Pp *  rr pp

RrPp (4), Rrpp (4), rrpp (8)

Walnut : Rose: Single

1:1:2