Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Catalytic activity is lost when the cofactor is removed from the enzyme. Reason (R): Cofactors are the protein components of the enzyme that determine its three-dimensional active site. In the light of the above statements, choose the most appropriate answer from the options given below.

Step-by-step solution

The Assertion is true because NCERT explicitly states that catalytic activity is lost when the cofactor is removed from the enzyme, which testifies that they play a crucial role in the catalytic activity of the enzyme. The Reason is false because cofactors are non-protein constituents bound to the enzyme to make it catalytically active. The protein portion of the enzyme is called the apoenzyme. Answer: Assertion is true but Reason is false.