10. before replication begins, the strands of DNA are separated and used as templates for the new strands. the replication process creates 2 identical double helixes, each has 1 new strand and 1 old one.
11. without dna replication, damaged cells could not be replaced/repaired and cells need dna, cells would become mutated without dna replication.
12. mutations are rare because dna polymerase proofreads the strands but if the process occurred incorrectly and was not corrected by the polymerase, the cell would become mutated and could be really harmful.
hope this helped!