Answer: Uric acid.
- A Urea
- B Uric acid
- C Ammonia
- D Creatinine
Correct answer: B. Uric acid
Explanation: Birds and reptiles are uricotelic, excreting nitrogenous waste mainly as uric acid, which is fairly insoluble and can be excreted with minimal water loss.
Filtrate flows through four functionally distinct stages of the nephron: Bowman's capsule filters blood, the PCT reabsorbs most useful substances unconditionally, the Loop of Henle builds a concentration gradient via counter-current exchange, the DCT secretes selected substances, and the collecting duct performs the final ADH-controlled water reabsorption.
Concept context
Nitrogenous waste, kidney structure, urine formation in the nephron, and hormonal regulation of excretion.
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