Birds excrete nitrogenous waste in the form of

Correct option is D

The correct answer is (d) uric acid

Explanation:
• Birds are classified as uricotelic organisms, meaning they excrete their primarily nitrogenous waste in the form of uric acid.
• Uric acid is extremely insoluble in water, allowing birds to excrete it as a semi-solid white paste. This serves as a vital adaptation to conserve body water.

Information Booster:
• Reptiles and terrestrial insects are also uricotelic, utilizing the same biological strategy for water conservation in arid environments.
• The production of uric acid requires more metabolic energy compared to urea or ammonia, but the extreme water savings justify the energy expenditure.

Additional Knowledge:
urea (Option a)
• Excreted primarily by mammals (including humans) and adult amphibians; such organisms are termed ureotelic.
ammonia (Option b)
• Excreted by most aquatic animals (ammonotelic organisms) like fish, as it is highly toxic and requires massive amounts of water for rapid dilution.
fatty acid (Option c)
• Fatty acids are an energy source and structural component of lipids, entirely unrelated to nitrogenous waste excretion.
None of the above/More than one of the above (Option e)
• Incorrect, as uric acid perfectly describes avian excretion.

So the correct answer is (d)