Question

Why do some animals prefer uricotelism over ureotelism?

• A. They have enough water available in their habitats
• B. They live in dry places and have to conserve water
• C. They are able to use uric acid as a poison in their defense mechanism against predators
• D. None of the above

Answer 1

Answer: (B)

They live in dry places and have to conserve water

Nitrogenous waste substances such as ammonia, urea, and uric acid are produced during protein metabolism. Ammonia is the most toxic and hence it has to be kept pretty diluted in order to protect the animal. So the animals having good access to water, like fishes use ammonotelism as their mode of excretion. Uric acid is the least toxic compared to the other two. Mammals and such animals who don't have unlimited access to water convert ammonia into slightly less toxic urea. But those animals who live in dry conditions or have limited access to water convert ammonia into uric acid which require less or no water and can be excreted in solid state and since it is less toxic, prefers uric acid as their excretory product.

So the correct answer is 'They live in dry places and have to conserve water'.