[Campbell Biology P.1041] Ostrich, like other birds, primarily excretes nitrogenous waste in ... | Practice Question

Ostrich, like other birds, primarily excretes nitrogenous waste in the form of uric acid. What is the main advantage of uric acid as a nitrogenous waste product for animals adapted to dry environments?

  • A: Uric acid is highly soluble in water, facilitating its easy excretion with minimal water loss.
  • B: Uric acid requires less metabolic energy to produce compared to other nitrogenous wastes like urea.
  • C: Uric acid precipitates out of solution and can be excreted with very little water, thus conserving fluid.
  • D: Uric acid is easily reabsorbed by the kidneys, preventing its loss from the body.

Explanation

Uric acid is less toxic and much less soluble in water than urea or ammonia. This allows it to be excreted as a semi-solid paste with very little water loss, which is a crucial adaptation for animals in dry environments like birds and most reptiles.