Read the passage carefully and answer the questions based on the passage:
Pest Resistance Plants
Various nematodes parasitize a wide variety of plants and animals, including human beings. A nematode Meloidogyne incognitia, infects the roots of tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi). RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO). GM plants have been useful in many ways. Genetic modification has: (i) made crops more tolerant to abiotic stresses (cold, drought, salt, heat). (ii) reduced reliance on chemical pesticides (pest-resistant crops). (iii) helped to reduce post harvest losses. (iv) increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil). (v) enhanced nutritional value of food, e.g. golden rice, i.e., Vitamin 'A' enriched rice. Genetic modification of organisms can have unpredictable results when such organisms are introduced into the ecosystem. Therefore, the Indian Government has set up organisations such as GEAC (Genetic Engineering Approval Committee), which will make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services. Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
RNA interference involves:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Silencing of specific mRNA due to complementary dsRNA
Option (1) Synthesis of cDNA and RNA using reverse transcriptase — Incorrect. Reverse transcriptase makes DNA from an RNA template; that is reverse transcription, not RNAi.
Option (2) Silencing of specific mRNA due to complementary dsRNA — Correct. A dsRNA binds to the matching mRNA and stops its translation.
Option (3) Interference of RNA in synthesis of DNA — Incorrect. RNAi acts on translation of an mRNA, not on DNA synthesis.
Option (4) Synthesis of mRNA from DNA — Incorrect. That is transcription, in which RNA polymerase copies a DNA strand into mRNA. RNAi does not make mRNA; it silences an mRNA that is already made.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.