What was the 2024 NEET question on prokaryotic RNA polymerase and sigma factor?
The correct option is A: Statement I is true and Statement II is false. Statement I affirmed that prokaryotic RNA polymerase catalyses transcription. Statement II claimed that transient sigma association is used for termination.
The four options were framed as:
This setup forces exact recall of initiation versus termination instead of general transcription knowledge.
What is the official step-by-step solution to the 2024 NEET RNA polymerase question?
Statement I is true because prokaryotic RNA polymerase alone catalyses transcription. Statement II is false because the sigma factor associates transiently with RNA polymerase specifically for initiation and promoter recognition.
Termination in prokaryotes is handled by rho factor in rho-dependent cases or intrinsic terminators. These checks match the verified NEET 2024 solution exactly. Therefore the correct option is A (I true, II false).
What exact mistake turns this 2024 NEET transcription question wrong?
Students treat sigma factor’s transient association as occurring at termination instead of initiation. This error causes them to mark both statements true and select option C.
The method mistake is failing to separate the three distinct stages of transcription and link each stage to its unique protein factor before judging the statement. Initiation needs sigma for promoter binding. Elongation proceeds with the core polymerase. Termination requires rho or hairpin signals.
Which core facts from NCERT Molecular Basis of Inheritance fix the sigma-rho confusion?
Prokaryotes have a single RNA polymerase that performs all transcription without needing separate enzymes. Sigma factor confers promoter specificity and is released after initiation.
Termination uses rho helicase in rho-dependent pathways or hairpin structures in rho-independent pathways. Sigma is initiation-specific while rho is termination-specific. Keep these mappings distinct and the statements evaluate themselves.
Can you solve these two practice questions on prokaryotic transcription factors?
Question 1 asks: What is the role of the sigma subunit in bacterial transcription initiation and why does it dissociate after promoter clearance? Sigma binds the core RNA polymerase to form the holoenzyme, recognises the promoter, and melts the DNA. It dissociates after promoter clearance because its job is complete and the core enzyme needs to move efficiently along the template. No further sigma is required until the next initiation event.
Question 2 asks: Name the protein factor responsible for rho-dependent termination in prokaryotes and contrast it with the role of sigma. Rho helicase is the factor for rho-dependent termination. It binds the nascent RNA at rut sites, uses ATP to translocate, and disrupts the elongation complex. Sigma acts only at initiation for promoter selection and has no role in termination. The two factors never operate at the same stage.
How do you solve assertion-reason questions on transcription in under 50 seconds?
Read both statements independently against NCERT facts before looking at options. Recall exact stage-specific factors (sigma equals initiation, rho equals termination) in under 10 seconds.
Next eliminate the three wrong combinations systematically rather than guessing. Target solving such questions in 40–50 seconds to stay on pace for 360 Biology marks across the 90 compulsory questions in the three-hour offline paper.
You can search the past-paper archive by chapter to find every similar Genetics and Evolution question from the last five years with worked solutions.
Why did NEET 2024 tag the RNA polymerase sigma factor question as hard?
It tests precise mapping of molecular players to transcription stages rather than broad process recall. The second statement deliberately swaps initiation and termination roles, a common NCERT mix-up.
This demands 50-second evaluation under pressure in a pen-and-paper OMR format. Photograph any remaining doubt for a step-by-step solution. Revise the stage-factor mappings before your next mock.
Next step: photograph a doubt on NEET JEEnius AI and photograph any question you are stuck on and get a step-by-step solution across Physics, Chemistry and Biology (20 free a month).
If that step was the hard part, work through Cannizzaro Reaction NEET 2026: Grignard Amine Question.
Frequently asked questions
What was the 2024 NEET question on prokaryotic RNA polymerase and sigma factor?
It was an assertion-reason question. Statement I: prokaryotic RNA polymerase catalyses transcription (true). Statement II: transient sigma association is used for termination (false). Correct option is A: I true, II false.
Is sigma factor used for termination in prokaryotes?
No. Sigma factor associates transiently only during initiation for promoter recognition and DNA melting. It is released after promoter clearance. Termination uses rho helicase in rho-dependent cases or hairpin structures in rho-independent cases.
Why is statement II false in the NEET 2024 transcription question?
Statement II incorrectly claims transient sigma association is for termination. Sigma is required only for initiation and promoter specificity. Termination is handled separately by rho factor or intrinsic terminators. This matches exact NCERT mapping of factors to stages.
How do you solve assertion-reason questions on transcription in prokaryotes?
Evaluate both statements independently against NCERT before seeing options. Recall sigma equals initiation and rho equals termination within 10 seconds. Eliminate the three wrong combinations systematically. This method finishes such questions in 40-50 seconds.
What is the role of sigma factor in bacterial transcription?
Sigma binds core RNA polymerase to form holoenzyme, recognizes promoter sequences and helps melt DNA during initiation. It dissociates after promoter clearance because the core enzyme handles elongation. No sigma is needed until the next initiation round.