1. Which enzyme is responsible for unwinding the DNA double helix during transcription? A) Helicase B) RNA polymerase C) Ligase D) Topoisomerase Answer: B) RNA polymerase Rationale: RNA polymerase is the enzyme that unwinds the DNA double helix and synthesizes mRNA by adding RNA nucleotides complementary to the DNA template strand. 2. What is the role of the promoter region in DNA transcription? A) Initiates replication B) Signals termination of transcription C) Binds RNA polymerase to initiate transcription D) Encodes for amino acids Answer: C) Binds RNA polymerase to initiate transcription Rationale: The promoter region contains specific DNA sequences that signal RNA polymerase where to begin transcription. 3. During transcription, which process occurs after RNA polymerase binds to the promoter? A) Elongation B) Termination C) Initiation D) Splicing Answer: A) Elongation Rationale: After RNA polymerase binds to the promoter, it begins to elongate the mRNA strand by adding complementary RNA nucleotides along the DNA template. 4. Which of the following is not a post-transcriptional modification of mRNA in eukaryotes? A) 5' capping B) Polyadenylation C) Splicing D) Methylation