Peptide linkage is present in:

In the given pentapeptide,find out an essential amino acid $(Y)$ and the sequence present in the pentapeptide: Choose the correct answer from the options given below:

The acid showing salt-like character in aqueous solution is

Which of the following amino acids contains an alcohol functional group?

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

Which protein is present in milk and eggs?