AP BIOLOGY

Detailed explanation-1: -Generally, aquatic animals excrete mostly ammonia, whereas terrestrial animals excrete either urea or uric acid. Ammonia, urea and uric acid are transported across cell membranes by different mechanisms corresponding to their different chemical properties in solution.

Detailed explanation-2: -Yes, urea is a nitrogenous waste. Excretion: Excretion is the process by which nitrogen-containing waste products of metabolism are eliminated from the body. The main source of nitrogenous waste in humans is Urea excretion is known as ureotelism, and the animals that do so are known as ureotelic animals.

Detailed explanation-3: -Urea is a major balancing osmolyte in marine cartilagenous fish, the coelacanth and a few amphibians and some aestivating terrestrial amphibians. It is a storage osmolyte in cocoon-forming aestivating lungfish and amphibians.

Detailed explanation-4: -The main excretory product generated by the human body is urea. It is generated by the breakdown of proteins in the liver where the excess amino acids are converted into urea. The urea is excreted out of the body via urine.