Question

Explain with an example for each, how the following provides evidence in favor of evolution in organisms.
(a) Homologous organs
(b) Analogous organs
(c) Fossils

Answer 1

Hint: Evolution is a change in the morphological and physiological characters of species as the characters pass on from one generation to another. Some anatomically different organs get modified for the same functions and vice versa.

Complete answer:
(a) Homologous organs are those organs that are inherited from the same ancestors and have the same structure, but due to evolution they now perform different functions. For example, Limbs of Human, Bat, and Mouse are strikingly similar but, humans write from hand-limbs, mice run, and bat flies. This similarity arises because they all share a common ancestor but differ in function due to evolution and to survive in their habitat. This is commonly known as divergent evolution
(b) Analogous organs are those organs that perform the same functions but have different ancestors and structures. For example, the wings of bats and birds have a different structure but perform the same function of flying. It is convergent evolution as despite having different ancestors they are performing the same functions.
(c) Fossils are the preserved remains and traces of previous life forms on the earth. They are considered as the most important and relevant evidence of evolution as it tells that life forms were different on earth before the present time or in other words it shows the progression of evolution. For example fossils of horses help in studying the evolution of species.

Note:
- The evolution term was coined by Charles Darwin.
- Molecular biology and comparative embryology are other shreds of evidence of evolution.