Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion : In presence of enzyme, substrate molecule can be attacked by the reagent effectively.
Reason : Active sites of enzymes hold the substrate molecule in a suitable position.
Enzymes hold the active sites of the substrate molecule in such a way so that the reagent can attack the substrate site effectively. Stereospecificity is one of the main properties of enzyme catalyzed reactions.