Question

(a) Differentiate between analogous and homologous structures.
(b) Select and write analogous structures from the list given:
(i) Wings of butterfly and birds
(ii) Vertebrate hearts
(iii) Tendrils of bougainvillea and Cucurbita
(iv) Tubers of sweet potato and potato.

Answer 1

Sr.no.	Analogous structures	Homologous structures
1.	They show superficial resemblance	They differ morphologically
2.	Their internal structure is quite different	They have similar internal structure.
3.	They develop in unrelated organisms	They develop in related organisms
4.	They have similar functions.	They perform different functions
5.	They have dissimilar developmental pattern.	They have similar developmental pattern.
6.	Analogous organs show convergent evolution.	Homologous organs show adaptive radiation (divergent evolution).

Table 1: Difference between Analogous and Homologous structures

(a) Homologous structures have similar morphology, embryology and anatomy etc. but are dissimilar in their functions. They are inherited from a common ancestor.

Example: Forelimbs of whales, bats, dogs, and human have similar anatomical structures.

Analogous structures are those structures which perform the same function, have similar appearance and structure but are not evolved together; therefore do not share a common ancestor.

Example: Wings of bird and wings of insects.

(b) The analogous structures from the list given are:

(i) Wings of butterfly and birds

(iv)Tubers of sweet potato and potato