Question

A useless or rudimentary body part that is thought to have been important in ancestral populations but no longer has a known function is termed a(n) ________.

1) evolved structure

2) terminal structure

3) vestigial structure

4) residual structure

Answer 1

A vestigial structure is a reduced or redundant body part that was once functional in an organism's ancestors, such as the human tailbone or appendix.

Step-by-step explanation:

A vestigial structure is a body part that has become diminished in size or usefulness in the course of an organism's evolution. These structures are considered to be remnants of features that were fully functional in the organism's ancestors but are now reduced or redundant. For example, the human tailbone or appendix, the hind leg bones in whales, and the wings on flightless birds like ostriches serve as vestigial structures, suggesting a change from use to disuse or a different purpose over evolutionary time.