Question

Identify the following pairs as homologous or analogous organs.
A. Sweet potato and potato
B. Eye of octopus and eye of mammals
C. Thorns of bougainvillea and tendrils of cucurbits
D. Forelimbs of bats and whales

Answer 1

Evolutionary investigations focus on two types of evidence, morphological and genetic. Homologous and analogous structures are evolutionary evidence of morphology. Homologous structures have the same embryonic region. Analogous structures have similar functions but superficial resemblance.

Complete answer:
Comparative anatomy and morphology show similarities and differences among organisms. Organisms adapt themselves to changing environments which results in changed appearances. Evolutionary biology describes two types of morphological differences,
- Homologous organs
- Analogous organs
- Homologous organs: it is a body part with the same structure but different functions. It is also called divergent evolution. It is important to track the evolutionary paths and also helps to recognize the same behavioral characteristics which are modified into different species with the changing environments.
- Analogous organs: these structures perform the same function, have similar appearance but are not evolved together. It is also called convergent evolution. Thus, do not share a common ancestor. These structures are a result of different ancestral origins unlike homologous structures.
Now, identification of given pairs as homologous or analogous.
- Sweet potato and potato: it is an example of analogous organs as they both have a common function of storage of food but differ in origin as potato is a stem tuber while sweet potato is a root tuber.
- Eye of octopus and eye of mammals: it is also an example of analogous organs as they both have different structures of eyes but serve the same purpose.
- Thorns of bougainvillea and tendrils of cucurbits: these are homologous organs. In bougainvillea thorns are from protection from predators and in cucurbits, tendrils serve the purpose of climbers. Thus, similar origin but different function.
- Forelimbs of bats and whales: these are also homologous organs, same origin and different functions. In bats, forelimbs help in grasping whereas in whales they help in swimming.

Note:
Apart from homologous and analogous evolutionary evidence, there is other evidence as well.
Fossil evidences- remains of ancestral organism
Molecular evidence- it includes traces of DNA, RNA, ATP, etc.
Embryological evidence- it uses ancestral embryos to study the pattern of evolution.