Biology Homeostasis PMDC Conceptual Practice
PMDC Verified Question 40 of 99
Which of the following nitrogenous waste compounds exhibits the highest solubility in water?
A
Urea
B
Ammonia
C
Uric Acid
D
Creatine
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Ammonia
Concept: Comparative solubility and toxicity of nitrogenous wastes.

Solution: Ammonia is extremely soluble in water (requiring ~500 mL of water per gram of nitrogen to dilute to non-toxic levels). This makes it the ideal excretory product for aquatic organisms.

Why other options are incorrect:
  • Option A (Urea): Moderately soluble in water; requires ~50 mL of water per gram of nitrogen.

  • Option C (Uric Acid): Almost insoluble in water; excreted as a semi-solid paste to conserve water.

  • Option D (Creatine): A nitrogenous organic acid involved in muscle energy storage, not a primary excretory waste product.

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