$A$ trait in an organism is influenced by

$(a)$ Which type of organs are shown in the figure below?
$(b)$ What is the origin and structure of these organs?

What is micro-evolution? Does it explain speciation?

Select the group which shares the maximum number of common characters.

In human males,all the chromosomes are paired perfectly except one. These unpaired chromosomes are:
$(i)$ Large chromosome
$(ii)$ Small chromosome
$(iii)$ $Y-$ chromosome
$(iv)$ $X-$ chromosome

$(a)$ What is geographical isolation?
$(b)$ Illustrate the formation of a species with the help of an example where individuals become very different from each other and are no longer capable of reproduction among themselves.