Enzymes lower activation energy in reaction energy diagrams

Steps:

• Identify key features: graphs show energy vs. reaction progress, with activation energy (Ea) as the peak from reactants to transition state.
• Compare without enzyme: high Ea barrier, same delta G (energy difference between reactants and products).
• Compare with enzyme: lowered Ea peak, identical delta G and end levels.
• Select graph matching both curves starting/ending at same points, enzyme curve with reduced hump.

Why C is correct:

• Matches enzyme catalysis definition: lowers Ea (per transition state theory) without altering delta G, speeding reaction rate.

Why the others are wrong:

• A: Shows enzyme changing delta G, violating thermodynamics (enzymes don't alter equilibrium).
• B: Depicts enzyme increasing Ea, opposite of catalytic effect.
• D: Lacks distinct curves or misplaces energy levels, ignoring unchanged reactant/product energies.

Final answer: C