Read the passage carefully to answer the questions given below.

Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). In Bacillus thuringiensis the toxin is coded by a gene crylAc named cry. There are a number of them, for example, the proteins encoded by the genes crylAc and cryllAb control the cotton bollworms, that of crylAb controls corn borer. Using conventional methods of diagnosis (serum and urine analysis, etc.) early detection is not possible. Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis. The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. The disorder is caused due to the deletion of the gene for adenosine deaminase. 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.

RNAi involves involves silencing of a specific mRNA due to a complementary _____ molecule that binds to and prevents translation of the mRNA.

dsRNA

The correct answer is Option (1) → dsRNA 

Several nematodes infect a wide variety of plants and animals including human beings. A nematode Meloidegyne incognitia infects the roots of tobacco plants which reduce the production of tobacco plants and reduces the production of tobacco. Thus, to prevent this infection a strategy is adopted known as RNA interface (RNAi) which takes place in all eukaryotic organisms as a method of cellular defence. This method involves silencing of mRNA due to complementary dsRNA molecule that binds to it and prevents the process of translation of mRNA.

The infection can be prevented using RNA interference process which is checked by silencing of specific mRNA due to a complementary ds RNA. The ds RNA binds and prevents translation of the mRNA. By using Agrobacterium vectors, nematode-specific genes were introduced into the host plants which produce both sense and antisense RNA in the host cells. These two RNAs are complementary to each other and form a double stranded RNA (ds RNA) that initiates RNAi and hence, silences the specific mRNA of the nematode. The parasite cannot survive in transgenic host and so, prevents the plants from pests.