The number of chromosomes in G${}_1$ phase of cell cycle is 24. What will be the number of chromosomes in the G${}_2$ phase?

The correct option is A 24
Cell undergoes cell cycle which includes a sequence of events during which the cell replicates its genetic material and then undergoes division. The cell cycle includes two phases - interphase and mitotic phase.

Interphase is a non dividing phase and includes G${}_1$, S and G${}_2$ phases in sequence. Cell divides during mitotic phase.

The DNA undergoes replication during S phase after which the total content of DNA doubles. The chromosome will now have two chromatids but the chromosome number does not increase and will remain the same as in G${}_1$ phase.

After S phase, the cell enters into G${}_2$ phase and during this phase, proteins needed for cell division are synthesised but with respect to DNA no changes occur. Hence, the cell in G${}_2$ phase will have the same number of chromosomes as in G${}_1$ and S phase.

As per the question given here, the cell has 24 chromosomes in G${}_1$ phase and the number shall remain the same during
G${}_2$ phase also. Hence, the cell at G${}_2$ phase will have 24 chromosomes.