The following events occur during the various phases of the cell cycle. Name the phase against each of the events.
$(a)$ Disintegration of nuclear membrane .........
$(b)$ Appearance of nucleolus
$(c)$ Division of centromere
$(d)$ Replication of $DNA$

The best stages to study the morphology and shape of a chromosome are respectively:

What is a syncytium?

Match the following columns correctly:

Column-$I$	Column-$II$
$(a)$ Number of cells in an adult human body	$(p)$ $90$ minutes
$(b)$ Average cell cycle duration of a human cell	$(q)$ $10^{14}$
$(c)$ Total sub-phases of Interphase	$(r)$ $24$ hours
$(d)$ Typical cell cycle duration of yeast	$(s)$ $3$

Select an incorrect statement with respect to the cell cycle.

Which of the following statements are correct?
$a -$ Cell cycle duration can vary from organism to organism and also from cell type to cell type.
$b -$ $DNA$ synthesis occurs only in pachytene.
$c - G_1$ phase corresponds to the interval between mitosis and initiation of $DNA$ replication.