Question

Which one of the following are analogous structures?
A.Wings of pigeon and wings of Eagle
B.Lungs of Man and Gills of Prawn
C.Tendrils of Cucurbita and thorns of Bougainvillea
D.Legs of Horse and flippers of dolphin

Answer 1

Scientists gather information which allows them to seek out about evolutionary connections among organisms. Evolutionary investigations concentrate on morphologic and genetic evidence. The body comprises many organs. These organs are classified as homologous and analogous organs.

Complete answer:
Analogous organs are defined as organs with different structural plans performing common functions.
Analogous organs:
• Not inherited from ancestors
• Result of convergent evolution
• Developed as a result of the difference to an identical environment

The presence of analogous structure, within the case of the wing, doesn't reflect evolutionary closeness among the organisms that possess it. Analogy is a facet of evolutionary biology and is distinct from homology, the similarity of structures as a result of similar embryonic origin and development, considered strong evidence of common descent.
In many cases analogous structures, or analogues, tend to become similar in appearance by a process termed convergence. An example is that the convergence of the streamlined form within the bodies of squid, shark, seal, porpoise, penguin, and ichthyosaur, animals of diverse ancestry. Physiological processes and behavior patterns may additionally exhibit analogous convergence. Egg-guarding behaviour within the cobra, octopus, and spider is believed to have evolved independently among those animals, which are quite distant in their biological relationships.

Example: Wings of insects and birds evolved independently in widely separated groups, and converged functionally to support powered flight.

Convergent evolution creates analogous structures that have similar form or function but weren't present within the last common ancestor of these groups. Lungs of man and gills of prawn demonstrate a similar structure. Hence they are analogous structures.

Hence, the correct answer is option (B)

Note: Some organisms might be closely related but few minor genetic change caused major morphological difference thus changing their appearance. Likewise, unrelated organisms could also be distantly related, but appear noticeably alike. This happens thanks to the common adaptation of both the organisms that evolved within similar environmental conditions. Therefore, in few cases similar characteristics occur because of environmental constraints and due to a detailed evolutionary relationship.