When your cat stalks and pounces on a bird, the cat is quiet, seemingly a cold-blooded killer, indicative of ___ aggression, but a cat when confronted by a bear arches its back, bristles its fur, and hisses menacingly at the bear is indicative of ___ aggression.

It would be like the 70's song "it's raining men".

Hormones are chemical molecules produced by glands

No, because  the definition of population is just a group of people. for example, if the population is that of sweden, the recessive trait, blond hair, is much more common than brown or black hair. but overall, dominant characteristics become more common over time. however, the dominant allele disease are extremely  rare, a lot  more then the recessive allele diseases.hope my answer has you : )