Question

I have a doubt in URECOTELISM process. The concept says that the uric acid is insoluble in water and it requires the least amount of water for excretion. But how is that possible, i can't understand., how an insoluble substance needs less water than ammonia and urea?

Answer 1

Uric acid is less toxic than ammonia or urea. It contains four nitrogen atoms and only a small amount of water (about 0.001 L per 1 g of nitrogen) is needed for its excretion. Uric acid is the least soluble in water. A single molecule of uric acid can remove four atoms of nitrogen making uricotelism more efficient than ammonotelism or ureotelism. Ammonia is toxic and it requires much water to remove from organism so it's produced primarily by water organisms which are not constraint by lack of water. Urea is less toxic and requires less water to remove from organism (so it's better in terrestrial environment) but it requires more energy to produce. And uric acid is most costly in terms of energy but requires the least amount of water to remove