We can answer this by asking firts Why do women live more than men? One of the significance is that death rates are higher for males than for females(e.g men die young because of accidents, suicide and homicide more than women). Another aspects is that even women suffer from more deseases, it seems that they could "deal" with them but men are killed rapidly beacuse of those deseases. there are many but I mentioned a few
Humans have approximately 24,000 genes, but fruit flies are not far behind, with approximately 14,000 genes.
A. because you can't observe an animal in its natural habitat if you take it out of its habitat or if you have a model.