[Campbell Biology P.1028] Which of the following statements accurately compares osmoregulatio... | Practice Question

Which of the following statements accurately compares osmoregulation in a marine bony fish and a freshwater bony fish, as described in the text and Figure 44.3?

  • A: Marine bony fish actively drink large amounts of water to compensate for water loss, while freshwater bony fish drink very little water.
  • B: Both marine and freshwater bony fish excrete large amounts of dilute urine.
  • C: Marine bony fish gain salts primarily by diffusion across gills, whereas freshwater bony fish excrete excess salts through gills.
  • D: Osmotic water gain is a significant problem for marine bony fish, while osmotic water loss is a problem for freshwater bony fish.

Explanation

Marine bony fish live in a hyperosmotic environment, constantly losing water by osmosis. They compensate by drinking large amounts of seawater and excreting excess salts through gills and scanty urine. Freshwater bony fish live in a hypoosmotic environment, constantly gaining water by osmosis. They compensate by drinking very little water, excreting large amounts of dilute urine, and actively taking up salts through gills and food.