How does the number of chromosomes in a sex cell compare with the number of chromosomes in the parent cell

Depending on the organism the number of in a cell may change

What function does the limb sever in each animal? how are the limb bones of the four animals similar? based on these similarities what can be inferred about the evolution of the four animals.

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -