ABCTE Biology Practice Exam

The excretory organ that belongs to arthropods is the Malpighian tubules. These structures are unique adaptations that enable arthropods, such as insects and arachnids, to efficiently excrete waste products while minimizing water loss.

Malpighian tubules work by transporting waste materials from the hemolymph (the fluid equivalent to blood in arthropods) into the tubules, where it is then emptied into the digestive tract and ultimately excreted. This system is advantageous for terrestrial arthropods, as it helps to conserve water in their often arid environments.

In contrast, flame bulbs are associated with flatworms and serve a different excretory function, while kidneys are found in vertebrates and play a role in filtering blood and forming urine. The option regarding an external pore does not specifically refer to a recognized excretory structure and lacks the functional specificity of the Malpighian tubules.