Biology Homeostasis PMDC Conceptual Practice
PMDC Verified Question 86 of 99
During states of dehydration, mammalian kidneys maximize water reabsorption because circulating hormones directly increase the:
A
Permeability of ascending limbs to salts
B
Solute concentration inside the renal pelvis
C
Glomerular filtration rate
D
Aquaporin permeability of collecting ducts to water
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Aquaporin permeability of collecting ducts to water
Concept: Endocrine compensation during dehydration.

Solution: High plasma osmolarity during dehydration triggers ADH release, which inserts aquaporin-2 channels into collecting duct membranes, enabling maximal water reabsorption into the hypertonic medulla.

Why other options are incorrect:
  • Option A: Ascending limb salt transport is driven by NKCC2 cotransporters, not acute hormonal water-channel changes.

  • Option B & Option C: Elevating GFR or pelvis solute concentration would increase water loss rather than conserve it.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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