Select the correct match for $X$ and $Y$:

Column $X$	Column $Y$
$(1)$ Chromosome	$(P)$ Genetic code
$(2)$ $m-RNA$	$(Q)$ Gene
$(3)$ $t-RNA$	$(R)$ Ribosome
$(4)$ $r-RNA$	$(S)$ Anticodon

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?

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$A$. Alfred Hershey and Martha Chase	$I$. Streptococcus pneumoniae
$B$. Euchromatin	$II$. Densely packed and dark-stained
$C$. Frederick Griffith	$III$. Loosely packed and light-stained
$D$. Heterochromatin	$IV$. $DNA$ as genetic material confirmation

Choose the correct answer from the options given below:

$A$ $DNA$ strand is directly involved in the synthesis of the following,except:

What is central dogma and describe the packing of $DNA$ helix?

How many of the following statements are correct?
$I - RNA$ is formed from $DNA$ by the process of transcription.
$II - DNA$ is more stable than $RNA$.
$III - RNA$ acts as a catalyst (enzyme) in some biochemical reactions.
$IV - DNA$ is resistant to mutations due to its double-helical structure and the presence of complementary strands that allow for repair mechanisms.