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Question #45735
The Question
In terrestrial mammals, Atrial Natriuretic Factor (ANF) acts as a crucial check on the Renin-Angiotensin mechanism to regulate blood volume and osmolarity. However, when a euryhaline teleost fish transitions from a marine environment to a freshwater river (experiencing hypotonic stress), ANF-like peptides fail to act as the primary master regulators of this osmotic shift. Which of the following best explains this physiological divergence?
Options
- A.
In teleosts, the primary osmoregulatory effector is the branchial epithelium (gills) regulated by the prolactin-cortisol axis, rendering the renal ANF-RAAS system subordinate.
- B.
Freshwater transition induces hypotonic stress, causing the teleost to actively drink water, a process regulated by ANF-induced vasodilation of afferent branchial arterioles.
- C.
ANF in teleosts acts synergistically with the Renin-Angiotensin system to maximize sodium excretion through their aglomerular kidneys.
- D.
The teleost kidney lacks the Loop of Henle, making it anatomically impossible for ANF to exert any vasodilatory effect on the vasa recta during hypotonic stress.
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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
ANF|Osmoregulation_in_Aquatic_Adaptations|Salt_Glands
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume the mammalian renal system (and its endocrine regulators like ANF, ADH, and RAAS) is the universal blueprint for vertebrate osmoregulation.
This question tests the 'Functional Location Trap' by requiring the student to recognize that in aquatic teleosts, the gills supersede the kidneys as the primary osmoregulatory effector, thereby shifting the master endocrine control away from the ANF-RAAS axis.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Excretory Products and Their Elimination - Class 11 |
| Concept | ANF Antagonism |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |