Question

The dotted line with label A on the graph represents which of the following?

• A. The amount of energy a reaction would need without an enzyme.
• B. The amount of energy a reaction would need with an enzyme.
  
• C. The speed of the reaction.
• D. The amount of energy needed to start the reaction with an enzyme.

Answer 1

Answer: (B)

The amount of energy a reaction would need with an enzyme.

Enzymes are biocatalysts which speed up the reactions. They do so by reducing the amount of activation energy required for a reaction to proceed. In the graph, the dotted line and the solid line shown in the activated complex area represent the activation energy required for a reaction to take place under 2 different circumstances. The dotted is lower than the solid line; indicating that the activation energy required for the reaction to occur is lower in the presence of 'A'. Thus, 'A' here represents an enzyme which is lowering the activation energy and increasing the rate of the reaction. So, the correct option is B