The centrosome duplicates during the

What change occurs in the nucleus of a cell as it progresses from the $G_1$ phase to the $G_2$ phase?

Chromatin fibres duplication,Genetic material-$4C$,Histone protein synthesis,Membranous organelle duplication,$DNA$ replication,centriole duplication. How many of the above features are associated with the synthesis $(S)$ phase of the cell cycle?

What is the typical duration of the cell cycle in a yeast cell?

In which stage of the cell cycle does the $DNA$ content increase from $2C$ to $4C$?

The fruit fly has $8$ chromosomes $(2n)$ in each cell. During interphase of mitosis,if the number of chromosomes at $G_1$ phase is $8$,what would be the number of chromosomes after $S$ phase?