The synthetic sweetener aspartame,known commercially as NutraSweet,is a methyl ester of a dipeptide. In aqueous solution on standing,it changes to:

The peptide that gives positive ceric ammonium nitrate and carbylamine tests is

Which of the following is an essential amino acid?

The substituents $R_1$ and $R_2$ for nine peptides are listed in the table given below. How many of these peptides are positively charged at $pH = 7.0$?

Peptide	$R_1$	$R_2$
$I$	$H$	$H$
$II$	$H$	$CH_3$
$III$	$CH_2COOH$	$H$
$IV$	$CH_2CONH_2$	$(CH_2)_4NH_2$
$V$	$CH_2CONH_2$	$CH_2CONH_2$
$VI$	$(CH_2)_4NH_2$	$(CH_2)_4NH_2$
$VII$	$CH_2COOH$	$CH_2CONH_2$
$VIII$	$CH_2OH$	$(CH_2)_4NH_2$
$IX$	$(CH_2)_4NH_2$	$CH_3$

Total number of essential amino acids among the given list of amino acids is . . . .
Arginine,Phenylalanine,Aspartic acid,Cysteine,Histidine,Valine,Proline

The correct statements are:
$A$. Activation energy for enzyme catalysed hydrolysis of sucrose is lower than that of acid catalysed hydrolysis.
$B$. During denaturation,secondary and tertiary structures of a protein are destroyed but primary structure remains intact.
$C$. Nucleotides are joined together by phosphodiester linkage between $C_{3}$ and $C_{5}$ carbons of the pentose sugar.
$D$. Quaternary structure of proteins represents the spatial arrangement of two or more polypeptide chains.
Choose the correct answer from the options given below: