75% rose comb 25% single comb
In chickens rose comb (R) is dominant to single comb (r). A homozygous rose combed rooster is mated with a single combed hen. All of the chicks in the F1 generation were kept together as a group for several years. They were allowed to mate only within their own group. What is the expected phenotype of the F2 chicks

given,

rose combed rooster (R)  ×  single combed hen (r)  

                                     RR × rr

                                          ↓

in F1 generation, all the chicks will be Rr

                                           ↓

in F2 generation, mating was done among their own group of Rr  

          Rr × Rr

               ↓

25% of RR   50% of Rr  and 25% of rr

phenotypes of chicks in f2 generation =  3:1 ( 75% rose combed as R is dominant and 25% single combed)

genotype = 1:2:1 ( 1/4 homozygous rose comb [RR] : 2/4 heterozygous rose comb [Rr] :1/4 homozygous single comb [rr])