Ncert Exercises & Solutions

Given below are two statements:

Assertion (A):	In presence of an enzyme, the substrate molecule can be attacked by the reagent effectively.
Reason (R):	Active sites of enzymes hold the substrate molecule in a suitable position.

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are FALSE.
3.	(A) is true but (R) is false.
4.	(A) is false but (R) is true.

Hint:

An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then

allows the products to dissociate (separate from the enzyme surface).

Thus, in the presence of an enzyme, the substrate molecule can be attacked by a reagent effectively because active Sites or

enzymes hold the substrate molecule in a suitable position. So, enzyme-catalyzed reactions are stereospecific reactions.

Hence, Assertion and reason both are correct statements and reason explains the assertion.