Biology Homeostasis PMDC Conceptual Practice
PMDC Verified Question 85 of 99
Marine bony fishes maintain osmotic balance in hypertonic seawater by drinking large quantities of seawater and producing:
A
Scanty, concentrated urine rich in divalent ions
B
Copious, dilute urine rich in water
C
Isotonic urine with zero salt content
D
Large volumes of urea-rich sweat
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Scanty, concentrated urine rich in divalent ions
Concept: Osmoregulation in marine teleosts.

Solution: Marine bony fishes lose water by osmosis across their gills. To compensate, they drink seawater and conserve water by excreting a small volume of concentrated urine containing excess divalent ions (\(\text{Mg}^{2+}\), \(\text{SO}_4^{2-}\)).

Why other options are incorrect:
  • Option B: Producing copious dilute urine is the osmoregulatory strategy of freshwater teleosts.

  • Option C & Option D: Marine bony fishes cannot produce zero-salt urine, nor do they possess sweat glands.

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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