DNA replication must create two sets of chromosomes.
Step-by-step explanation:
Mitosis is where the cell divides itself into two identical parts.
In order for the two cells to be identical, they need to have the same parts, which is where replication is important
If the cell didn't replicate its organelles, it would not be able to split itself since nothing would go into one of the halves
Replication is the duplication of those organelles so that the sister cells are the same, so making a copy of the nucleus and other organelles allows one of those parts to stay and one part to go into the new cell