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Question #46708
The Question
A researcher compares the gastric pepsin of a frog (Rana tigrina) with a functionally equivalent protein-digesting enzyme from an invertebrate predator. Both enzymes efficiently hydrolyze the same dietary proteins. However, a specific competitive inhibitor completely blocks the invertebrate enzyme but fails to inhibit the frog's pepsin. Based on the principles of evolution and enzyme kinetics, which of the following statements is the most accurate explanation?
Options
- A.
The enzymes are homologous structures resulting from divergent evolution, causing the frog's pepsin to lose its affinity for the competitive inhibitor.
- B.
The enzymes are analogous molecules resulting from convergent evolution; therefore, their active sites possess different amino acid residues despite functional similarity.
- C.
The frog's pepsin exhibits divergent evolution, altering its substrate recognition site to bind the inhibitor non-competitively.
- D.
The invertebrate enzyme operates via an induced-fit mechanism, whereas the frog's pepsin relies strictly on a lock-and-key mechanism, preventing inhibitor binding.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Frog Digestive Enzyme Specificity|Analogous Organ Structure
Why This Question Is Tricky
Common Mistakes
The Conceptual Pivot lies in distinguishing between functional convergence and structural homology.
Students often assume that if two enzymes digest the same substrate, they must have identical active sites.
This question forces the synthesis of Class 12 Evolution (Analogous organs/Convergent evolution) with Class 11 Biomolecules (Competitive inhibition and active site specificity).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Structural Organisation in Animals - Class 11 |
| Concept | Frog Digestive Enzyme Specificity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |