Enzyme helpful in polymerizing RNA with defined sequences in a template independent manner is:

Polynucleotide phosphorylase

The correct answer is Option (2) → Polynucleotide phosphorylase

Explanation:

Polynucleotide phosphorylase:

• Severo Ochoa enzyme (polynucleotide phosphorylase) is helpful in polymerising RNA with defined sequences in a template independent manner (enzymatic synthesis of RNA).
• It uses nucleotide diphosphates as substrates and can create RNA with defined sequences without requiring a DNA or RNA template.

Mononucleotide phosphorylase:

• This is not an enzyme involved in RNA polymerization.

RNA polymerase I:

• It is a eukaryotic enzyme that synthesizes rRNA in a template-dependent manner.

DNA-dependent RNA polymerase:

• This enzyme synthesizes RNA based on a DNA template and is involved in transcription.

Key Point:

The distinguishing factor is that Polynucleotide phosphorylase does not require a template, unlike RNA polymerases which are always template-dependent.