During $DNA$ transcription,$mRNA$ is usually single-stranded. However,sometimes an $RNA$ molecule is produced that is complementary to the $mRNA$. This is called ...... and its function is to ...... .

In $lac$ operon,$z$ gene codes for:

What does '$1$' represent in the given figure?

Who proposed the operon model for the first time?

In $lac$ operon,the regulator gene codes for

Which of the following statements concerning the regulatory gene $(i)$,associated with the $lac$ operon are incorrect?
$(I.)$ $\text{mRNA}$ is transcribed from the $i$ gene whether lactose is present or not.
$(II.)$ $\text{mRNA}$ is transcribed from the $i$ gene only when the lactose is present.
$(III.)$ $\text{mRNA}$ is transcribed from the $i$ gene only when the lactose is not present.
$(IV.)$ Lactose inhibits the translation of $i$ gene $\text{mRNA}$.