Enzymes facilitate reactions by lowering activation energy

Steps:

• Statement 1 is correct: Enzymes bind substrates in active sites, positioning reactive groups for efficient collision.
• Statement 2 is correct: Enzymes lower activation energy (Ea), so a greater proportion of molecules surpass the energy barrier at ambient temperatures.
• Statement 3 is correct: Without enzymes, many reactions require high temperatures; enzymes enable them at physiological conditions like 37°C.
• All three statements align with enzyme catalysis principles, selecting option A.

Why A is correct:

• Enzymes function as catalysts by reducing Ea (per transition state theory), increasing reaction rates via proximity (1), energy efficiency (2), and lower temperature feasibility (3).

Why the others are wrong:

• B ignores statements 2 and 3, which describe key energy and temperature effects.
• C excludes statement 2, but lowering Ea increases reactive molecules.
• D omits statement 1, but substrate orientation is essential for catalysis.

Final answer: A