Which pairs of animals show a correct example of homologous structures? a. Wings of butterfly and bat. b. Flipper of whale and forelimb of cat. c. Fingers of human and arm of starfish. d. Tongue of frog and proboscis of mosquito.
The correct answer and explanation is:
The correct answer is:
b. Flipper of whale and forelimb of cat.
Explanation:
Homologous structures are anatomical features in different species that have a similar basic structure due to shared ancestry, even if their functions may differ. These structures arise from a common evolutionary origin but may have adapted to different environments or uses over time.
Why option b is correct:
- The flipper of a whale and the forelimb of a cat are examples of homologous structures because both share the same underlying bone structure (humerus, radius, ulna, carpals, metacarpals, and phalanges).
- Although the whale’s flipper is adapted for swimming and the cat’s forelimb is adapted for walking and running, their similar skeletal makeup reflects common ancestry from a tetrapod (four-limbed vertebrate) ancestor.
- This structural similarity despite functional differences is the key characteristic of homology.
Why the other options are incorrect:
- a. Wings of butterfly and bat:
These are analogous structures, not homologous. Butterfly wings are made of chitin and are part of an insect’s exoskeleton, while bat wings are modified forelimbs with bones. They evolved independently for the same function (flight) but do not share a common ancestral structure. - c. Fingers of human and arm of starfish:
Humans are vertebrates with limbs supported by bones, while starfish are echinoderms with a very different body plan and no true bones or limbs. Their “arms” are not homologous to human fingers. - d. Tongue of frog and proboscis of mosquito:
These serve very different functions and originate from different tissues. The frog’s tongue is muscular and used for catching prey, while the mosquito’s proboscis is a specialized feeding structure. They do not share common evolutionary origins.
Summary:
Homologous structures indicate evolutionary relationships through similar anatomy inherited from a common ancestor. The whale flipper and cat forelimb fit this definition, making option b the correct choice. Other pairs either serve similar functions but have different origins (analogous) or are too distantly related to have homologous features.