The human species $(Homo\,sapiens)$ have genetic roots in $......$

Homologous organs are different from analogous organs. Mention the two basic characteristics that decide about analogy and homology between the two organs.

New species may be formed if
$(i)$ $DNA$ undergoes significant changes in germ cells
$(ii)$ chromosome number changes in the gamete
$(iii)$ there is no change in the genetic material
$(iv)$ mating does not take place

In human beings, sex is determined by:

In which organisms is a higher degree of variation observed?

$(a)$ Explain why the wing of a bat and the wing of a bird are considered to be analogous organs.
$(b)$ List two factors that lead to the formation of a new species.