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प्रश्न
In RNAi genes are silenced using ______.
पर्याय
ss DNA
ds DNA
ds RNA
ss RNA
उत्तर
In RNAi genes are silenced using ds RNA.
Explanation:
RNAi is a cellular defense mechanism found in all eukaryotic species. This method involves the silencing of a specific mRNA by a complementary ds RNA molecule binding to the mRNA and preventing it from being translated (silencing). Infection with viruses with RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediary could be the source of this complementary RNA.
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Insects in the Lepidopteran group lay eggs on maize crops. The larvae on hatching feed on maize leaf and tender cob. In order to arrest the spread of three such Lepidopteran pests, Bt maize crops were introduced in an experimental field.
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The lepidopteran pests were allowed to feed on the same Bt-maize crops grown on 5 fields (A-E).
The graph below shows the leaf area damaged by these three pests after feeding on maize leaves for five days.
Key for lepidopteran insect pest species
 |
Species I |
 |
Species II |
 |
Species III |
Insect gut pH was recorded as 10, 8 and 6 respectively for Species I, II and III respectively.
(a) Evaluate the efficacy of the Bt crop on the feeding habits of the three species of stem borer and suggest which species is least susceptible to Bt toxin.
(b) Which species is most susceptible to Bt-maize, and explain why?
(c) Using the given information, suggest why a similar effect was not seen in the three insect species.
