Birds that fly have lightweight bones some of which are hollow how might this unique body structure benefit the bird?

Hollow lightweight bones benefit the bird by letting it fly. If the bird had regular bones like any other animal, then the bird wouldn't have the ability to be able to fly due to the extra weight.

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.