When you compare different organisms and see that they have the same or similar anatomic traits, it's reasonable to assume the organisms share a common ancestor where they would have gotten trait from. (evolution)
Answer:
prokaryotes and eukaryotes I believe
There is a 50/50 chance of there being a male or female. The mother puts off the X chromosome, while the father is the factor that can make the gender. The X chromosome is female, while the Y chromosome is the male. The father can either put off the X or Y.
