Biology Homeostasis PMDC Conceptual Practice
PMDC Verified Question 82 of 99
Which of the following nitrogenous metabolic wastes exhibits the lowest toxicity to biological tissues?
A
Uric acid
B
Ammonia
C
Urea
D
Bilirubin
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Uric acid
Concept: Comparative toxicity of nitrogenous wastes.

Solution: Uric acid is non-toxic and insoluble in water, allowing it to be safely stored in tissues or excreted as a paste without causing osmotic or chemical damage.

Why other options are incorrect:
  • Option B (Ammonia): Extremely toxic; disrupts cellular pH and membrane potentials.

  • Option C (Urea): Moderately toxic; requires dilution in water for safe transport and excretion.

  • Option D: Bilirubin is a bile pigment from hemoglobin breakdown, not a primary nitrogenous waste.

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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