What is the primary nitrogenous waste excreted by terrestrial insects?

What is the primary nitrogenous waste excreted by terrestrial insects?

• A. Ammonia
• B. Urea
• C. Creatinine
• D. Uric acid

Answer: (D)

Terrestrial insects waste nitrogen in a form optimized for life on land: uric acid. This compound is relatively insoluble and can be excreted as a dry paste or crystals, which lets the insect shed nitrogen with very little water loss. Ammonia, while cheap to make, is highly toxic and needs huge dilution with water to be safely excreted, which isn’t feasible for land-dwelling organisms. Urea is more soluble in water and isn’t as well suited to conserve water, and creatinine is more typical of vertebrate metabolism. So, by evolving to excrete uric acid, terrestrial insects maximize water retention while still removing excess nitrogen.

Terrestrial insects waste nitrogen in a form optimized for life on land: uric acid. This compound is relatively insoluble and can be excreted as a dry paste or crystals, which lets the insect shed nitrogen with very little water loss. Ammonia, while cheap to make, is highly toxic and needs huge dilution with water to be safely excreted, which isn’t feasible for land-dwelling organisms. Urea is more soluble in water and isn’t as well suited to conserve water, and creatinine is more typical of vertebrate metabolism. So, by evolving to excrete uric acid, terrestrial insects maximize water retention while still removing excess nitrogen.