Question

Which of the following is a metabolic waste of protein metabolism?
(a)${ NH }_{ 3 }$, urea, and ${ CO }_{ 2 }$
(b)Urea, oxygen, and ${ N }_{ 2 }$
(c)Urea, ammonia, and alanine
(d)Urea, ammonia, creatinine

Answer 1

Hint: The protein metabolism occurs and the by-products will get excreted from the body. One of the by-products is highly toxic to our body and it causes a burning sensation in the eyes, nose, causes blindness and liver damage. The other product is released during protein break down in the muscles.

Complete answer:
The nitrogenous wastes are nitrogen-containing compounds through which excess nitrogen will be eliminated from various organisms. Ammonia, urea, uric acid, and creatinine are produced by protein metabolism. In many animals, the urine remains as the main route of excretion of these wastes such wastes and in some, the excretion will be via feces.
Ammonotelism: The ammonia and ammonium ions excretion is known as ammonotelism. The oxidation of amino groups will form ammonia. The amine groups are removed from the proteins and the proteins are converted into carbohydrates. Ammonia is highly toxic to tissues, it is soluble in water and thus lots of water is required for ammonia excretion. Some marine organisms will excrete ammonia directly into the water and are known as ammonotelic. Examples of ammonotelic animals are protozoans, cnidarians, platyhelminthes, etc.,
Ureotelism: Ureotelism is the excretion of urea. The conversion of ammonia to urea will take place in some land animals (ureotelic animals), as the urea is less toxic than ammonia. This process will take place in the liver and kidney. Excretion of urea requires less water for excretion.
Uricotelism: The excretion of excess nitrogen as uric acid is known as Uricotelism. Birds, reptiles, and insects are Uricotelic animals. It requires higher metabolic energy for the uric acid formation than urea. However, the less toxicity and low solubility of uric acid in the water is an advantage.
So, the correct answer is, ‘Urea, ammonia, and creatinine’.

Note: The conditions during which we intake lots of protein, deamination will take place in which the amino acids will be broken down to obtain energy. Deamination is the process by which an amino group will be removed from the molecule. Enzymes that are involved in the catalysis of this reaction are called deaminases.