What is the main determining factor of the boundary between the layers

Which heredity condition causes a buildup of mucus in lungs and pancreas? a. cystic fibrosis b. heart disease c. huntington's disease d. sickle cell anemia

The image shows the evolution of a species of fish. a few fish from a population developed different social behaviors and evolved into different species. two fish according to the image, the fish underwent . the new species of fish had mating seasons that were different from that of the original fish. because of the differences in mating seasons, the fish underwent reproductive isolation. this mode of isolation would be .

Crossing over is a method of (blank)?