Which one of the following correctly represents the manner of replication of $DNA$?

Read the following four statements ($1$ to $4$):
$1$. In transcription,uracil pairs with adenosine.
$2$. Regulation of $lac$ operon by a repressor is referred to as positive regulation.
$3$. The human genome contains approximately $50,000$ genes.
$4$. Haemophilia is a sex-linked recessive disease.
How many of the above statements are correct?

Segment of $DNA$ which is responsible for inheritance and expression of a particular character is known as

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$A$. Monocistronic gene	$I$. Coding sequence
$B$. Polycistronic gene	$II$. Intervening sequence
$C$. Exons	$III$. Mostly prokaryotes
$D$. Introns	$IV$. Mostly eukaryotes

Match the following in column $I$ with column $II$ and choose the correct combination.

Column $I$	Column $II$
$a.$ Termination	$i.$ Aminoacyl $t-RNA$ synthetase
$b.$ Translation	$ii.$ Okazaki fragments
$c.$ Transcription	$iii.$ $GTP$ dependent release factor
$d.$ $DNA$ replication	$iv.$ $RNA$ polymerase

$DNA$ generally acts as a template for the synthesis of: