Question

which action is one role of rna polymerase during transcription?

○ to produce a start sequence

○ to break down an already existing protein

○ to build a molecule of mrna

○ to switch uracil with thymine on the exposed gene

Explanation:

• Option "to produce a start sequence": Start sequences (like promoters) are DNA regions, not produced by RNA polymerase during transcription.
• Option "to break down an already existing protein": RNA polymerase is involved in nucleic acid synthesis, not protein breakdown (that's proteases).
• Option "to build a molecule of mRNA": During transcription, RNA polymerase uses DNA as a template to synthesize mRNA (messenger RNA), which is a key role.
• Option "to switch uracil with thymine on the exposed gene": RNA has uracil, DNA has thymine; RNA polymerase incorporates uracil (not switch) and works on DNA template, so this is incorrect.

Answer:

C. to build a molecule of mRNA (assuming the options are labeled A - D with C being the third option as marked in the image)