Enzyme role in lowering activation energy

• A. Lower activation energy and align reactants for reaction
• B. Increase activation energy
• C. Are consumed during reaction
• D. Change equilibrium constant

Answer: (A)

Activation energy is the energy barrier that must be overcome for reactants to convert into products. Enzymes act as biological catalysts by providing an alternative pathway with a lower energy barrier. They do this mainly by lining up the substrates precisely in the active site and stabilizing the transition state through specific interactions with amino acids and cofactors. This arrangement reduces the entropic cost of bringing reactants together and lowers the energy required to reach the transition state, speeding up the reaction.

Enzymes are not consumed in the reaction, so they can be reused. They also do not change the overall equilibrium constant because they do not alter the free energy difference between reactants and products; they simply accelerate both the forward and reverse directions by lowering the activation energy. They do not increase activation energy, which would slow the reaction.