Question

In terms of evolution, why might the urea cycle have evolved in organisms?

a) To regulate body temperature.
b) To provide structural support to cells.
c) To facilitate the excretion of nitrogenous wastes.
d) To enhance the sense of smell in organisms.

Answer 1

The urea cycle evolved in organisms primarily to enable the safe excretion of nitrogenous wastes, especially as life forms moved from aquatic to terrestrial habitats. It conserves water and allows organisms to adapt to environmental changes.

Step-by-step explanation:

In terms of evolution, the urea cycle may have evolved in organisms to facilitate the excretion of nitrogenous wastes. This biochemical pathway became critical as life transitioned from aquatic to terrestrial environments, where conserving water was essential. In mammals, the urea cycle efficiently converts toxic ammonia to urea, which is less toxic and can be safely stored and excreted. In contrast, birds, reptiles, and insects primarily use the uric acid cycle, which conserves even more water, an adaptation beneficial in arid environments.

The evolution of the urea cycle likely occurred because it allows organisms to adapt to the changing environment by securely handling and excreting ammonia as urea. This evolutionary step was crucial for survival as it enabled organisms to colonize new habitats with varying resource availability and climatic conditions.