In DNA replication, which term describes the region of DNA that is unwound to serve as the template for replication?

In DNA replication, which term describes the region of DNA that is unwound to serve as the template for replication?

• A. The region where DNA is fully double-stranded
• B. The portion of DNA that is unwound to be replicated
• C. The site of RNA transcription
• D. The enzyme that catalyzes primer synthesis

Answer: (B)

The key idea is that DNA must be opened up to expose templates for copying. The region where the double helix has been unwound at the replication fork becomes the single-stranded templates that DNA polymerases use to synthesize new strands. Among the choices, describing the portion that is unwound to be replicated directly captures this exposed template region, which is what polymerases read during replication. The other options point to regions or activities not describing the unwound template region: a fully double-stranded area isn’t available for replication, transcription occurs with RNA polymerase, and primer synthesis is done by an enzyme, not a region of DNA.

The key idea is that DNA must be opened up to expose templates for copying. The region where the double helix has been unwound at the replication fork becomes the single-stranded templates that DNA polymerases use to synthesize new strands. Among the choices, describing the portion that is unwound to be replicated directly captures this exposed template region, which is what polymerases read during replication. The other options point to regions or activities not describing the unwound template region: a fully double-stranded area isn’t available for replication, transcription occurs with RNA polymerase, and primer synthesis is done by an enzyme, not a region of DNA.