Reproduction is essential for living organisms in order to

$(a)$ Name the parts labelled as $A, B, C$ and $D$ in the diagram given below:
$(b)$ What is pollination? State its significance.
$(c)$ How does fertilization occur in flowers? Name the parts of the flower that develop into $(i)$ seed,and $(ii)$ fruit after fertilization.

Write true or false for the following statement: Menstruation lasts for about ten to fifteen days.

Is the chromosome number of the zygote,embryonal cells,and adult of a particular organism always constant? How is the constancy maintained in these three stages?

Mention one function each of the following parts with respect to the female reproductive system:
$(a)$ Vagina
$(b)$ Ovary

$(a)$ Identify the asexual method of reproduction in each of the following organisms:
$(i)$ Rose
$(ii)$ Yeast
$(iii)$ Planaria
$(b)$ What is fragmentation? Name a multicellular organism which reproduces by this method.