Down syndrome most often occurs when

Which of the following sex and generation combinations directly produces the pollen tube of angiosperms? a) male gametophyteb) female gametophytec) male sporophyted) female sporophyte

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins

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 .