pH Denatures Enzyme Active Site

Steps:

• Enzymes like amylase have optimal pH for activity; graph likely shows peak rate then decline between X and Y.
• Extreme pH alters enzyme structure via ionization of amino acids.
• This changes active site conformation, reducing substrate binding.
• Result: decreased maltose production, explaining graph's downward shape.

Why C is correct:

• Enzyme-substrate complex follows lock-and-key model; pH-induced shape change disrupts fit, lowering reaction rate per enzyme kinetics.

Why the others are wrong:

• A: Incomplete and irrelevant; does not address pH effect on enzyme.
• B: Kinetic energy relates to temperature, not pH; enzyme works but inefficiently due to structure.
• D: Substrate kinetic energy is constant and unrelated to pH-specific decline.

Final answer: C