The destruction of $50\%$ of maize plants in the $USA$ in $1970$ was due to an infection by:

For which variety of Indian rice was the patent filed by a $USA$ company?

Transgenic plants are produced by $......$.

Cry-$1$ endotoxins,which are obtained from $Bacillus$ $thuringiensis$,are effective against ...........

Read the statements and choose the correct option.
$Statement I$: $RNAi$ takes place in all prokaryotic and eukaryotic organisms as a method of cellular defence.
$Statement II$: $RNA$ interference is a pre-translational process.

Consider the following statements about $Bt$:
$I.$ The bacteria $Bacillus$ $thuringiensis$ $(Bt)$ are used to control butterfly caterpillars.
$II.$ Fresh spores of $Bt$ are mixed with water and sprayed on crops such as brassicas and fruit trees.
$III.$ Insect larvae,after eating these,are killed by the toxin released in their gut.
$IV.$ $Bt$ toxin genes have been introduced into plants to provide resistance to pests.
Which of the statements given above are correct?