(a) What are carbohydrates? And how are they classified?
(b) What is a peptide bond? How many peptide bonds are present in a tetra peptide?

Explanation

(a) Optically active polyhydroxy aldehydes or ketones or those compounds which yield these on hydrolysis.
Classified as monosaccharides, oligosaccharides, polysaccharides.
(b) Elimination of a water molecule from two molecules of similar or different amino acids and formation of - CONH-bond.
3 - peptide bond are present in tetra peptide.