Question

do homologous structures always perform the same function?

Answer 1

During evolution different species may have evolved from a common ancestor. Such species may have organs which are similar in structure. Such organs are known as homologous structures. These organs may or may not perform similar function in the different species.

The most common example of homologous structure is forelimb found in humans, birds, whales. In humans the forelimb in arm performs various functions but is not involved in movement of humans. In birds the forelimb is present in wings and is necessary for flight. In whales, the forelimb like structure is present in the flipper and is necessary for swimming. Thus, in birds and whales, the forelimb is involved in locomotion whereas in humans it is not.