Question

An example of homologous organs is
a. Our arm and a dog’s fore-leg
b. Our teeth and an elephant’s tusks
c. Potato and runners of grass
d. All of the above

Answer 1

Hint: Homologous organs are those organs which have the same basic structural design and origin but the functions are different. The structure of the two different animals resembles but the function of their organs varies.

Complete answer:
There are two types of structures by which we can trace the evolutionary relationships between organisms.
• Analogous organs: The analogous structures in different organisms have similarity in their functions but different anatomically structured. The analogous structures do not exhibit common ancestry.
• Homologous organs: The homologous structures in different organisms have similarity in their anatomy but serve different functions. This similarity in their anatomy is due to the phenomenon of common ancestry.

Homologous structures are the result of divergent evolution. Divergent evolution is the process in which organisms from the common ancestor evolve and accumulate differences, resulting in the formation of new species. Divergent evolution occurs in response to change in abiotic factors (change in environmental changes) and biotic factors (increase in competition between the same species).

The heart in various vertebrates such as fishes, amphibians, reptiles, birds and mammals show similarity in the basic plan but they have varied degrees of specialization.
Homologous structures can also be seen in the plants. One of the examples in plants is the thorn of Bougainvillea and tendrils of cucurbita.

Hence, the correct answer is option (D).

Note: Homology can be seen at the molecular level such as proteins found in the blood of man and ape are similar and we can trace the similar genes in different organisms which points towards the common ancestor.