Which enzyme is the principal catalyst that synthesizes new DNA strands during DNA replication?

• A. DNA ligase
• B. DNA polymerase
• C. Helicase
• D. Primase

Answer: (B)

Verified step by step guidance

1. Understand the role of each enzyme listed in the context of DNA replication.
2. Recall that DNA ligase is responsible for joining Okazaki fragments on the lagging strand, not synthesizing new DNA strands.
3. Recognize that helicase unwinds the DNA double helix to provide single-stranded templates but does not synthesize DNA.
4. Know that primase synthesizes short RNA primers needed to start DNA synthesis but does not extend the DNA strand itself.
5. Identify DNA polymerase as the enzyme that adds nucleotides to the growing DNA strand by reading the template strand, thus synthesizing new DNA.