- Desert animals have longer loop of Henle compared to that of humans. It may be due to the following reasons:
A. Long loop of Henle is associated with greater amount of vasopressin secretion.
B. In long loop of Henle, the counter-current exchanger is more effective.
C. Long loop of Henle conserves more water.
D. Long loop of Henle stimulates production of angiotensin II.
Which of the above reason(s) is/are correct?
(1) A and B (2) B and C
(3) C and D (4) Only DDesert animals face extreme challenges in maintaining water balance due to the scarcity of water in their environments. One crucial anatomical adaptation is having longer loops of Henle in their kidneys compared to humans, allowing them to conserve more water.
Reasons for Longer Loops of Henle in Desert Animals
A. Association with Vasopressin Secretion
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This is incorrect.
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Vasopressin (antidiuretic hormone) controls water permeability in collecting ducts but is not directly related to the loop length.
B. More Effective Counter-Current Exchanger
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This is correct.
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Longer loops of Henle establish a larger osmotic gradient in the kidney medulla through the counter-current multiplier system.
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This increased gradient allows more water to be reabsorbed from the collecting duct, significantly conserving water.
C. Longer Loop Conserves More Water
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This is correct.
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The ability to produce highly concentrated urine reduces water loss.
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Desert animals such as camels and kangaroo rats rely on this to survive with minimal water intake.
D. Stimulation of Angiotensin II Production
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This is incorrect.
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Angiotensin II, part of the renin-angiotensin system, helps regulate blood flow and sodium retention but does not influence loop length.
Summary of Correct Reasons
Reason Correctness Long loop linked to vasopressin secretion Incorrect More effective counter-current exchanger Correct Conserves more water Correct Stimulates angiotensin II production Incorrect Conclusion
The adaptations explaining why desert animals have longer loops of Henle are:
(2) B and C
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