$(i)$ Name the scientist who proposed the theory of evolution of species by natural selection.
$(ii)$ What conclusion did Mendel draw from his experiments regarding traits?
$(iii)$ Arrange the following organisms in the order of their evolutionary complexity: Cockroach,Mango tree,Gorilla,Fish.

(N/A) $(i)$ Charles Darwin proposed the theory of evolution by natural selection.
$(ii)$ Mendel concluded that traits are inherited independently,which is known as the Law of Independent Assortment.
$(iii)$ The evolutionary order from simplest to most complex is: Mango tree (Plant) $-$ Cockroach (Invertebrate) $-$ Fish (Lower Vertebrate) $-$ Gorilla (Higher Vertebrate/Mammal).