Question

The diagram illustrates energy changes in activation energy of uncatalysed and enzyme catalysed reaction. Which of the following option represents the lowering of the activation energy?

• A. X - Y
• B. Y - Z
• C. X - Z
• D. Z - Y

Answer 1

The correct option is D Z - Y

The energy required to initiate a reaction is known as the activation energy, Ea. The bold curve shows the un-catalysed reaction with $E_a=z,$ whilst Y represents the $E_a$ of the catalysed reaction (dotted curve). The $E_a$ is thus lowered by (Z - Y).