Question

Define activation energy for biological reactions.

Answer 1

In relation to biology (such as biochemistry), the activation energy (or energy of activation) pertains to the energy needed to initiate a reaction. For instance, the activation energy required to breakdown glucose into pyruvic acid in respiration is two ATP.
Accordingly, enzymes speed up chemical reactions by reducing the activation energy of a reaction. Moreover, this reduction by an enzyme allows biological reactions to proceed rapidly at relatively low temperatures tolerable by living organisms.