To understand how this works, look at the alleles collectively, normal chickens with a single comb are always recessive rrpp for both alleles.
Throw in a dominant R, and you get a rose comb
Throw in a dominant P and you get a pea comb
If you have one of each RP, then you get the buttercup phenotype
1. On the cross pictured, what must be the genotypes of the two parents for the outcome to always be a buttercup offspring?
____rrPP____ x ______RRpp_____
2. Show a Punnett square for the following cross and describe the phenotypic ratios.
RrPp x RrPp
You can use the 9:3:3:1 ratio to solve this one
9 R_P_ = buttercup
3 R_pp = rose
3 rrP_ = pea
1 rrpp = single
3. Show a punnett square for the following cross and describe the phenotypic ratios.
Single comb x Buttercup (RrPp)
rrpp x RrPp
1/4 RrPp = buttercup
1/4 Rrpp = rose
1/4 rrPp = pea
1/4 rrpp = single
4. Show a punnett square for the following cross and describe the phenotypic ratios.
Single comb x Pea comb (rrPp)
rrpp x rrPp
1/2 rrPp = pea
1/2 rrpp = single
5. A rose crossed with a pea produces six buttercup and five rose offspring. What must be the genotypes of the parents?
RRpp x rrPp
I look at this one with what would need to happen to produce 0 pea offspring. In this case the no rr can be found in the offspring
In the cross about offspring will be RrPp = buttercup and Rrpp = rose, about half and half