Question

The diagram illustrates energy changes in an enzyme controlled reaction.

Which of the following represents the lowering of the activation energy?

• A. X
• B. Y
• C. Z
• D. Z - Y

Answer 1

Answer: (D)

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