Explain (in one or two lines) the function of the following:
$(a)$ Promoter
$(b)$ $tRNA$
$(c)$ Exons

If the base sequence of one strand of $DNA$ is $CAT, TAG, CAT, CAT, GAC$,what would be the base sequence of its complementary $RNA$?

Which enzyme helps in the process of $DNA$ transcription?

What is the effect of the association of various factors with $RNA$ polymerase?

Match Column-$I$ with Column-$II$ and select the correct answer from the options given below.

Column-$I$	Column-$II$
$i$. Cistron	$a$. Addition of methylated $GTP$ to $5'$-end of $hnRNA$.
$ii$. Exon	$b$. Non-coding sequences which are removed by splicing.
$iii$. Intron	$c$. Segment of $DNA$ coding for a polypeptide.
$iv$. Capping	$d$. Coding sequences which appear in processed $mRNA$.

Given below are two statements, one is labelled Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A) :$ In eukaryotes, primary transcripts $(hnRNA)$ contain both exons and introns, and introns are non-functional.
Reason $(R) :$ In bacteria, the $mRNA$ does not require any processing, and transcription and translation take place in the same compartment.
In the light of the above statements, choose the most appropriate answer from the options given below $:$