The advantage of excreting wastes as urea rather than as ammonia is that
A)urea can be exchanged for Na+.
B)urea is less toxic than ammonia.
C)urea requires more water for excretion than ammonia.
D)urea does not affect the osmolar gradient.
E)less nitrogen is removed from the body.

Question

Quizplus · Accepted Answer

Urea is less toxic than ammonia, so excreting waste as urea is safer for the organism. Ammonia is highly toxic and can damage cells and tissues. Urea is also more water-soluble than ammonia, so it can be excreted with less water loss. However, urea still requires some water for excretion, so it cannot be exchanged for Na+ like ammonium ions can be. The osmolar gradient may still be affected by the excretion of urea, but not as significantly as with ammonia. Overall, excreting wastes as urea is a more efficient and less toxic process than excreting wastes as ammonia.

The Advantage of Excreting Wastes as Urea Rather Than as Ammonia