Question

What are excretory substances? How is ammonia produced?

Answer 1

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Excretion is a process in which metabolic waste is eliminated from an organism.

Ammonia (i.e. total NH3 and NH4+, TAmm) is produced by nearly all living cells, usually as the nitrogenous waste product of amino acid catabolism, degradation of purines and pyrimidines, and probably through the 'purine nucleotide cycle' of invertebrates (Campbell, 1991; Larsen et al., 2014).