Which of the following describes the given graph correctly? (Graph shows reaction-coordinate / potential-energy profile with activation energies labelled 'A' and 'B'.)
Answer: (B) Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme. Answer: (B) Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme.
- A.Endothermic reaction with energy A in presence of enzyme and B in absence of enzyme
- B.Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme✓
- C.Endothermic reaction with energy A in absence of enzyme and B in presence of enzyme
- D.Exothermic reaction with energy A in absence of enzyme and B in presence of enzyme
Correct Answer
(B) Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme
Solution & Explanation
Answer: (B) Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme. Solution: In the energy profile the product (P) lies at a lower energy than the substrate (S), so the reaction is exothermic. An enzyme works by bringing down the activation-energy barrier, so the smaller barrier 'A' is the activation energy WITH enzyme and the larger barrier 'B' is WITHOUT enzyme. Hence the curve shows an exothermic reaction with A (enzyme present) lower than B (enzyme absent). NCERT Reference: Ch 9, p.115, line ~24 — "Enzymes eventually bring down this energy barrier making the transition of 'S' to 'P' more easy"