The 'Operon model' for gene regulation in bacteria was proposed by:

In eukaryotes,the regulation of gene expression could be exerted at $:-$
$(I)$ Transcriptional level (formation of primary transcript)
$(II)$ Processing level (regulation of splicing)
$(III)$ Transport of $\text{mRNA}$ from nucleus to the cytoplasm
$(IV)$ Translational level
Choose the correct order for given statements $:-$

Two scientists were awarded the Nobel Prize in $2006$ for $RNA$ interference. On which organism did these scientists discover this mechanism?

Which of the following would you expect to find in an inducible system?

The $lac \, y$ gene codes for which of the following?

Structural gene is monocistronic $- P$
Structural gene is polycistronic $- Q$
Select the correct option for $P$ and $Q$.
$\quad\quad\quad P \quad\quad Q$