During dna replication, a primer attaches to a template strand of dna and begins a new strand. after the primer has attached, an enzyme extends the new strand of dna by adding nucleotides that correspond to the nucleotide sequences in the template strand. which enzyme is responsible for adding nucleotides to the growing dna molecule?

The enzyme that is responsible for adding nucleotides to the growing DNA molecule is called DNA POLYMERASE. 
The principal role of DNA polymerase is to carefully and accurately add the right nucleotides to the growing DNA molecule in order to make sure that the genome is accurately replicated and the genetic information are maintained.