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

$A$ tetrapeptide $x$ on complete hydrolysis produced glycine $(Gly)$,alanine $(Ala)$,valine $(Val)$,and leucine $(Leu)$ in equimolar proportions. The number of possible tetrapeptide sequences involving each of these amino acids exactly once is:

The number of peptide bonds in the compound is:

What does the secondary structure of proteins represent?

Which one of the following is an amino acid?

In an oligopeptide named Alanyl-glycyl-phenyl-alanyl-isoleucine,the number of $sp^2$ hybridised carbons is $...........$.