Give scientific reasons: $DNA$ polymerase plays a dual function during $DNA$ replication.

(N/A) $DNA$ polymerase performs a dual function during $DNA$ replication:
$1$. Polymerization: It catalyzes the addition of deoxyribonucleotides to the $3'$ end of the growing $DNA$ strand, facilitating the synthesis of new $DNA$ strands.
$2$. Proofreading and Repair: It possesses $3' \to 5'$ exonuclease activity, which allows it to remove incorrectly paired bases (mismatched nucleotides) and replace them with the correct ones, ensuring high fidelity of replication. Additionally, it is involved in the removal of $RNA$ primers and filling the gaps with $DNA$ fragments.