Question

In presence of an enzyme, the activation energy

• A. Increases
• B. Decreases
• C. First increases and then decreases
• D. Activation energy in not affected at all

Answer 1

The correct option is B Decreases

There is an energy barrier between substrate and products, the energy required for alignment of reacting groups, formation of transient unstable charges, bond rearrangements, and other transformations required for the reaction to proceed. This is illustrated by the energy hill. The difference between the energy levels of the ground state and the transition state is the activation energy. The rate of a reaction reflects this activation energy : a higher activation energy corresponds to a slower reaction. Reaction rates can be increased by raising the temperature, thereby, increasing the number of molecules with sufficient energy to overcome the energy barrier. Alternatively, the activation energy can be lowered by adding a catalyst (enzyme). Catalysts enhance reaction rates by lowering activation energies.