Nitrogenous waste is excreted in the form of pellet or paste by:

Correct answer: 1)

Concept:

• Excess nitrogen in the form of nitrogenous waste is excreted from the body in three forms, that is, ammonia, urea, and uric acid.
• The most toxic nitrogenous waste is ammonia.

Explanation:

a) Ammonotelic

• The organisms that excrete ammonia as nitrogenous waste are known as ammonotelic organisms.
• Ammonia is highly toxic.
• It is highly soluble in water, and therefore requires plenty of water for its excretion.
• Example: bony fishes (like Hippocampus) and aquatic amphibians (like Salamandra).

b) Ureotelic

• Humans and other mammals  (like Ornithorhynchus) excrete urea as nitrogenous waste.
• They are known as ureotelic organisms.
• Urea is less toxic and needs less water in comparison to Ammonia.  
• It is can be stored in cells without toxic effects.

c) Uricotelic

• Birds, insects, reptiles, and land snails all excrete uric acid as nitrogenous waste.
• These organisms are known as uricotelic organisms.
• Pavo is the name of the bird, and it is uricotelic in nature, it excretes out waste in the form of a pellet or paste.

• Needs very little water to get rid of uric acid

So, the correct answer is option 1.