Activation energy is best defined as the energy
- A. released when the products are formed
- B. stored in the bonds of the substrate
- C. needed to bring the reactants to the transition state so the reaction can proceed
- D. used by the enzyme to bind the substrate
Explanation
Even an energetically favourable reaction needs an initial input to break existing bonds and reach the unstable transition state, and that barrier is what keeps sugars from spontaneously oxidising in the air. An enzyme lowers the barrier by stabilising the transition state, so far more molecules can cross it at body temperature. The energy difference between reactants and products is a separate quantity that the enzyme does not change.