[Campbell Biology P.1041] Which of the following statements accurately compares the osmoregul... | Practice Question
Which of the following statements accurately compares the osmoregulatory adaptations of marine bony fishes, freshwater fishes, and birds?
A: Marine bony fishes have extensive loops of Henle to excrete concentrated urine, unlike freshwater fishes which primarily excrete dilute urine.
B: Birds possess juxtamedullary nephrons with loops of Henle that extend as far into the medulla as those of mammals, allowing for high urine concentration.
C: Freshwater fishes, being hyperosmotic to their surroundings, produce large volumes of dilute urine, whereas marine bony fishes excrete little urine and rely on gill chloride cells for salt balance.
D: Both birds and most other reptiles excrete urea as their primary nitrogenous waste, an adaptation for water conservation.
Explanation
Freshwater fishes are hyperosmotic to their surroundings and produce large volumes of dilute urine to excrete excess water. Marine bony fishes excrete little urine and actively secrete salts via chloride cells in their gills to maintain salt balance. Birds, unlike mammals, have loops of Henle that extend less far into the medulla and excrete uric acid for water conservation, not urea.