A Level Biology Practice Exam

What defines analogous structures in biology?

1. Structures with the same origin but different functions

2. Structures that have adapted to perform the same function but have a different origin

3. Structures that are morphologically similar and share a common ancestor

4. Structures that are identical in function and anatomy

The correct answer is: Structures that have adapted to perform the same function but have a different origin

Analogous structures in biology are defined as those that have evolved to perform the same function but have different evolutionary origins. This means that although the structures may serve a similar purpose in different organisms, they do not share a common ancestor, which sets them apart from homologous structures, which do share a common origin. An example of analogous structures would be the wings of bats and the wings of insects; both are adapted for flight, demonstrating how different species can evolve similar traits as they adapt to comparable ecological niches despite their different evolutionary backgrounds. This concept highlights the role of convergent evolution, where unrelated species develop similar adaptations in response to environmental challenges.