• Statement (I) is True: During feedback inhibition (allosteric inhibition), the end-product of a biosynthetic pathway binds to an allosteric regulatory site of an early pathway enzyme already present in the cell, rapidly suppressing its catalytic activity post-translationally.
• Statement (II) is True: During enzyme repression, the accumulating end-product acts as a corepressor, binding to an aporepressor to form an active repressor that silences promoter transcription, thereby shutting down the de novo synthesis of the enzyme at the genetic level.
• Conclusion: Both Statement (I) and Statement (II) are true.

Correct option: (1) Both Statement (I) and Statement (II) are true.

• Assertion (A) is True: Orally active pharmaceutical agents achieve optimal bioavailability when they exist in dynamic equilibrium between unionized (lipophilic, capable of diffusing across hydrophobic intestinal lipid membranes) and ionized (hydrophilic, capable of aqueous dissolution in blood and target interaction) forms at physiological pH (~7.4).
• Reason (R) is True & Explains (A): Drugs designed with dissociation constants ($pK_a$) in the physiological window of 6.0 to 8.0 maintain substantial fractions of both neutral and ionized species as predicted by the Henderson-Hasselbalch equation:

• Conclusion: Both (A) and (R) are true and (R) is the correct explanation of (A).

Correct option: (1) Both (A) and (R) are true and (R) is the correct explanation of (A)

• Statement (I) is False: Competitive enzyme inhibition is classically reversible; because the competitive inhibitor binds non-covalently to the catalytic substrate-binding pocket, it can be completely displaced by increasing substrate concentration ($[S]$).
• Statement (II) is False: In competitive inhibition, the apparent maximum velocity remains completely unchanged ($V_{\max}^{\text{app}} = V_{\max}$). It is the apparent Michaelis constant ($K_m$) that increases by the factor $\alpha$ ($K_m^{\text{app}} = \alpha K_m$).
• Conclusion: Both Statement (I) and Statement (II) are false.

Correct option: (2) Both Statement (I) and Statement (II) are false.

• Serine Protease Catalytic Triad: Chymotrypsin is a pancreatic endopeptidase belonging to the Serine Proteases superfamily.
• Catalytic Mechanism: It utilizes an invariant catalytic triad composed of Ser195, His57, and Asp102. The histidine acts as a general base to deprotonate Ser195, generating a potent alkoxide nucleophile that attacks the substrate carbonyl carbon to form a covalent acyl-enzyme intermediate.

Correct option: (2) Serine Proteases