Biomedical Admissions Practice Test

Answer: A, Anatomical features in different species that suggest a common ancestor are called homologous structures. These structures in different species are different enough that it is likely they both descended from the same progenitor.

Key Takeaway: Unlike analogous structures, homologous structures in different species typically perform different functions. Examples of homologous structures are the arm of a human and the flipper of a whale. The structures clearly have different functions and definitely do not resemble each other at first glance. However, a closer look at their bone structures demonstrates a great of similarity between the two, which is indicative of two species that descended from a common ancestor. As further proof, all vertebrate animals share this same limb structure.