In poultry, two genes, R and P, control the shape of the comb on the head. The following genotype/phenotype relationship applies to these two genes: R- P- animals have a 'walnut' comb; R- pp animals have a 'rose' comb; rr P- animals have a 'pea' comb; rr pp animals have a 'single' comb. What will the comb phenotypes of the progeny be for a cross of rr PP X rr Pp animals

100% of the progeny will have a pea comb, rrP-

Explanation:

Available data:

Cross:

Parentals)      rrPP          x        rrPp

Gametes) rP, rP, rP, rP        rP, rP, rp, rp

Punnett square)     rP     rP      rP      rP

                    rP    rrPP   rrPP   rrPP  rrPP

                    rP    rrPP   rrPP   rrPP  rrPP

                    rp    rrPp   rrPp   rrPp   rrPp

                    rp    rrPp   rrPp   rrPp   rrPp

F1) Genotype

    Phenotype

    16/16 = 100% of the progeny will have a pea comb

i think its the first one

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.