Polytene chromosomes in salivary glands of Drosophila are formed as a result of

Match the following columns correctly:

Column $I$	Column $II$
$(a)$ $G_1$ phase	$(p)$ Synthesis of new $DNA$ occurs
$(b)$ $G_2$ phase	$(q)$ No $DNA$ synthesis occurs
$(c)$ $S$ phase	$(r)$ $DNA$ synthesis stops
$(d)$ Prophase	$(s)$ Formation of mitotic spindle occurs

Chromosomes become short,dense,and distinct,each chromosome consists of a centromere and two chromatids,and the nucleolus and nuclear envelope disappear. During which phase are these changes observed?

Which stages of cell division do the following figures '$A$' and '$B$' represent respectively?

Select the correct option for the following matches:

List-$I$	List-$II$
$(1)$ Metaphase-$I$	$(a)$ Number of chromosomes becomes half of the parent cell
$(2)$ Anaphase-$I$	$(b)$ Each chromosome splits at the centromere to form chromatids
$(3)$ Anaphase-$II$	$(c)$ Homologous chromosomes form pairs at the equatorial plate
$(4)$ Telophase-$II$	$(d)$ Homologous chromosomes move towards opposite poles

Agglutination of chromosomes is caused by a mitotic poison called