Final answer:
DNA replication occurs before cell division to ensure each daughter cell receives an identical copy of the DNA. Incomplete DNA replication can lead to genetic mutations and disorders.
Step-by-step explanation:
DNA replication occurs before cell division to ensure that each daughter cell receives an identical copy of the DNA. During DNA replication, the DNA molecule unwinds and each strand serves as a template for the synthesis of a new complementary strand. This process produces two identical DNA molecules that can be distributed to the daughter cells during cell division.
If cell division took place without DNA replication, each daughter cell would only have half of the DNA, resulting in a loss of genetic information. If DNA replication was incomplete, errors could occur in the DNA sequence, leading to mutations and genetic disorders.