A pheasant breeder starts with two birds in the P generation, one of which is AA and the other is aa. If he takes two of the birds from the F1 generation and breeds them together, what genotypes can he expect in his F2 offspring?

AA, Aa and aa  genotypes will be produced.

Explanation:

If two birds with AA and aa genotypes are crossed, 4 offspring with Aa phenotype may be produced in F1 generation.

P generation:                      AA   x aa

                                           /   \        /  \

F1 generation:                Aa  Aa  Aa  Aa

When these F1 generation birds will be allowed to breed, the genotype of the F2 offspring will be as under:

                                    Aa    x  Aa

                                    /   \        /  \

F2 generation:       AA   Aa  Aa  aa

3 types of genotypes AA, Aa and aa will be produced in F2 generation. Their ratio will be AA : Aa : aa = 1 : 2 : 1.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

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