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

Amino acids behave like salts rather than simple amines or carboxylic acids. Explain.

Which among the following $\alpha$-amino acids does $NOT$ have a chiral carbon atom?

The non-essential amino acid among the following is

Proteins are polymers of $\alpha$-amino acids,which are linked by peptide bonds. Chemically,proteins are:

$\alpha$-$helix$ is a secondary structure of proteins formed by twisting of polypeptide chain into right-handed screw-like structures. Which type of interactions are responsible for making the $\alpha$-$helix$ structure stable?