[Campbell Biology P.1032] Which of the following statements accurately compares the three mai... | Practice Question

Which of the following statements accurately compares the three main forms of nitrogenous waste ammonia, urea, and uric acid in animals?

  • A: Ammonia is the least toxic and requires the least water for excretion, while uric acid is the most energetically expensive to produce.
  • B: Urea is highly soluble and less toxic than ammonia but more energetically costly to produce than uric acid.
  • C: Uric acid requires the least water for excretion and is relatively nontoxic, but its synthesis demands more energy than urea.
  • D: All three forms of nitrogenous waste are equally soluble in water and require similar amounts of energy for their synthesis.

Explanation

Uric acid is excreted as a semisolid paste with very little water loss, making it advantageous in arid environments. It is relatively nontoxic but is the most energetically expensive to produce compared to ammonia and urea. Ammonia is highly toxic and requires large volumes of water, while urea is less toxic and soluble, but still requires more water than uric acid for excretion and is less energetically expensive to produce than uric acid.