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Question #45456
The Question
In terrestrial mammals, Atrial Natriuretic Factor (ANF) acts as a crucial vasodilator and natriuretic agent. If mammalian ANF is experimentally administered to a freshwater teleost, it fails to produce a comparable massive sodium-wasting effect. Based on the evolutionary divergence of osmoregulatory mechanisms, which of the following best explains this observation?
Options
- A.
Terrestrial mammals evolved ANF as a specific physiological antagonist to the robust RAAS required for land survival, whereas freshwater teleosts rely primarily on gill-based ionocytes and lack this specific RAAS-ANF antagonistic axis.
- B.
Freshwater teleosts possess a hyperactive RAAS to excrete excess water, which competitively overrides the vasodilatory and natriuretic effects of the administered mammalian ANF.
- C.
The two-chambered heart of teleosts lacks the specific atrial receptors required for ANF binding, as endocrine cardiac tissue is an exclusive evolutionary feature of tetrapods.
- D.
ANF acts as a potent vasoconstrictor in aquatic environments to decrease the Glomerular Filtration Rate (GFR), thereby preventing the loss of essential electrolytes.
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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
Evolutionary Chronology|Natural Selection Directionality|ANF
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'ANF decreases BP' without understanding its evolutionary context as a specific antagonist to RAAS (a terrestrial adaptation).
The trap lies in failing to distinguish between mammalian renal-based osmoregulation (RAAS/ANF) and aquatic gill-based osmoregulation, leading to functional confusion about how these hormones operate across different taxa.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Atrial Natriuretic Factor (ANF) |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |