Question

The standard free energy change and standard activation energy for four biochemical reactions are listed in the table below.

Reaction	Standard free energy change (kcal/mol)	Standard activation energy (kcal/mol)
P	-40	18
Q	-71	18
R	-40	11
S	-71	11

A few interpretations are given below. Among these, the most appropriate interpretation is

• A. P, Q, R and S represent the same reaction carried out in the presence of enzyme, high temperature, absence of enzyme and low temperature, respectively.
• B. Q and S represent the same reaction carried out at high and low temperatures, respectively
• C. R and S represent the same reaction carried out in the presence and absence of catalyst, respectively
• D. P and R represent the same reaction carried out in the absence and presence of enzyme, respectively

Answer 1

Answer: (D)

Standard free energy represents the energy available to do work at standard temperature. Activation energy represents the energy required to start a reaction. The enzyme works by lowering down the activation energy.