(a) Carbohydrates that give large number of monosaccharide units on hydrolysis / large number of monosaccharide units joined together by glycosidic linkage starch/ glycogen/ cellulose (or any other)
(b) Proteins that lose their biological activity / proteins in which secondary and tertiary structures are destroyed Curdling of milk (or any other)
(c) Amino acids which cannot be synthesised in the body.

Valine/Leucine (or any other)
OR
(a) When D-glucose reacts with conc. ${\mathrm{HNO}}_3$, it forms saccharic acid.
(b) In aqueous solution, the carboxyl group present in amino acid can lose a proton and the amino group can accept a proton to form zwitter ion.
This zwitter ion can act both as an acid and a base showing amphoteric behaviour.
$\mathrm{R}-\underset{{\mathrm{NH}}_2}{\underset{|}{\mathrm{CH}}}-\stackrel{\mathrm{O}}{\stackrel{\parallel }{\mathrm{C}}}-{\mathrm{O}}^{-}$ $\underset{{\mathrm{OH}}^{-}}{\overset{{\mathrm{H}}^{+}}{\rightleftharpoons }}\mathrm{}\mathrm{R}-\underset{{\mathrm{NH}}_2}{\underset{|}{\mathrm{CH}}}-\stackrel{\mathrm{O}}{\stackrel{\parallel }{\mathrm{C}}}-{\mathrm{O}}^{-}$ $\underset{{\mathrm{OH}}^{-}}{\overset{{\mathrm{H}}^{+}}{\rightleftharpoons }}\mathrm{}\mathrm{R}-\underset{{}_{}^{+}{\mathrm{NH}}_2^{}}{\underset{|}{\mathrm{CH}}}-\stackrel{\mathrm{O}}{\stackrel{\parallel }{\mathrm{C}}}-\mathrm{OH}$
(c) $\mathit{\alpha }$-helix has intramolecular hydrogen bonding while $\mathit{\beta }$ pleated has intermolecular hydrogen bonding / $\mathit{\alpha }$-helix results due to regular coiling of polypeptide chains while in $\mathit{\beta }$ pleated all polypeptide chains are stretched and arranged side by side.