Question

Choose the correct statement(s) with reference to organic evolution.
I. Flippers of whales and wings of bats exhibit analogy.
II. Wings of butterflies and wings of birds exhibit homology.
III. Organs with dissimilar structures, performing similar functions are called analogous organs.
IV. Organs with similar structure and origin are called homologous organs.

Answer 1

Homologous organs are those organs which are similar in the origin and have the same basic structure but differ in the functions they perform.
For example, cats, bats and whales are vertebrates. They indicate common ancestry. The function of forelimbs in all these animals is different, but the basic structure and development pattern of the forelimbs is similar. Hence, they are examples of homologous organs.

Flippers of whales and wings of bats are homologous organs, hence statement I is incorrect. Statement IV is correct as the homologous organs have the same embryonic origins and basic structure, but they do not perform the same function.

Analogous organs are the organs which have different basic structural design but they perform similar functions. The development of similar characteristics in unrelated species over time is called convergent evolution.

Statement II is incorrect as wings of butterflies and wings of birds are analogous organs. Wings of butterflies and wings of birds perform the same function, helping animals to fly but they have different internal structures.

Statement III is correct as the analogous organs have dissimilar structures but perform the same function.