$A$ dipeptide,$X$ on complete hydrolysis gives $Y$ and $Z$. $Y$ on treatment with aqueous $HNO_2$ produces lactic acid. On the other hand,$Z$ on heating gives the following cyclic molecule.
Based on the information given,the dipeptide $X$ is:

Which of the statements about "Denaturation" given below are correct?
$1.$ Denaturation of proteins causes loss of secondary and tertiary structures of the protein.
$2.$ Denaturation leads to the conversion of double strand of $DNA$ into single strand.
$3.$ Denaturation affects primary structure which gets distorted.

Column-$I$	Column-$II$
$A$. Tyrosine	$P$. Essential amino acid
$B$. Serine	$Q$. Ceric Ammonium Nitrate
$C$. Tryptophan	$R$. Neutral $FeCl_{3}$
$D$. Proline	$S$. Carbylamine Test - Negative

Select the correct set of answer :

Discuss the structure and shape of proteins.

Which synthesis was done by Stanley Miller?

Identify the basic amino acid from the following.