At the surface of enzyme, active sites are present. These active sites of enzymes hold the substrate molecule in a suitable position, so that it can be attacked by the reagent effectively. This reduces the magnitude of activation energy.

Enzymes contains cavities of characteristics shape and possessing active groups known as active centre on the surface. The molecules of the reactant (substrate) having complementary shape, fit into these cavities. On account of these active groups, an activated complex is formed which then decomposes to yield the products.

All naturally occurring $\alpha$-amino acids (except glycine) are optically active due to the presence of chiral carbon atom. These have either $D$ - or L-configuration. $D$-form means that, the amino $\left(-\mathrm{NH}_2\right)$ group is present towards the right hand side. $L$-form shows the presence of $-\mathrm{NH}_2$ group on the left hand side.

$1^{\circ}$ and $2^{\circ}$ hydroxyl groups present in glucose can be identified by the reaction of glucose with nitric acid. Primary OH group present in glucose are easily oxidise to $-$COOH group while secondary OH group does not.

Hence, one OH is primary OH group.

Denaturation of proteins Protein present in egg white has an unique three dimensional structure. When it is subjected to physical change like change in temperature. i.e., on boiling, coagulation of egg white occurs due to denaturation of protein. During denaturation hydrogen bonds are disturbed due to this globules unfold and helix gets uncoiled and protein looses its biological activity.

A. $\rightarrow(3,6)$ B. $\rightarrow$ (7) C. $\rightarrow$ (1) D. $\rightarrow$ (8) E. $\rightarrow(4,9) \quad$ F. $\rightarrow(5)$ G. $\rightarrow$ (2)