Ammonotelism – Class 11 | Chapter – 19 | Biology Short Notes Series PDF
Ammonotelism refers to the process of excretion of nitrogenous waste substances by certain organisms, in form of ammonia. Excretion refers to the process of removal of unwanted and harmful products from the body. The excretory system removes all the waste substances from our bodies, especially nitrogenous waste. The process of excretion is important for the body as it aids the removal of waste from the body along with excess vitamins, bile pigments, and salts. The five modes of excretion are Ammonotelism, Uricotelism, Aminotelism, Ureotelism, and Guanotelism.
Other terms associated with ammonotelism are:
(i) Ureotelism: Excretion of urea.
The chemical processes taking place in the liver and kidney convert ammonia into urea. Urea is less toxic than ammonia. Animals, mainly amphibians and mammals, show this process and are called ureotelic.
(ii) Uricotelism: Excretion of excess nitrogen in the form of uric acid. The organisms like insects, birds and most reptiles are uricotelic animals.
Physiological Aspect of Excretion of Ammonotelism
- Fishes and other aquatic organisms consume dietary-rich protein food. These organism intestines are adapted for the deamination of amino acids as they cannot store them for an extended time.
- The deamination reaction (conversion of proteins into carbohydrates) produces uric acid. This uric acid is oxidized to allantoin and allantoic acid.
- The hydrolysis of allantoin to allantoate and further hydrolysis results in the formation of urea and glyoxylate.
- In ammonotelic organisms, urea is further broken down into ammonia and carbon dioxide.
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Much of the ammonia is produced from alpha-amino groups present in dietary feed.
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