Which from the following is an essential amino acid?

Assertion: $\alpha$-amino acids exist as internal salt in solution as they have amino and carboxylic acid groups in near vicinity.
Reason: $H^{+}$ ion given by carboxylic group $(-COOH)$ is captured by amino group $(-NH_2)$ having lone pair of electrons.

Which one of the following biomolecules is insoluble in water?

Hydrolysis of proteins gives

How many tripeptides can be prepared by linking the amino acids glycine,alanine and phenylalanine?

Protein can be most easily removed from which of the following?