Homologous Organs & Analogous Organs - Practice Questions & MCQ

• Comparative anatomy and morphology show similarities and differences among organisms of today and those that existed years ago.
• Such similarities can be interpreted to understand whether common ancestors were shared or not. 

Homologous Organs:

• The organs which have the same fundamental structure but the difference in functions are called homologous organs.
• These organs follow the same basic plan of the organization during their development but in the adult condition, these organs are modified to perform different functions as an adaptation to the different environment.
• These are the results of divergent evolution.
• Homology indicated common ancestry.

Examples of Homologous Organs:

• The forelimbs of man, cheetah, whale and bat.
  • Used for grasping in man
  • Used for running in cheetah
  • Used for swimming in whales
  • Used for flying in bats
• Mouthparts of cockroach, honey bee, mosquito and butterfly.
  • Used for biting and chewing in cockroaches
  • Used for chewing and lapping in honey bees
  • Used for piercing and sucking in mosquitoes
  • Used for siphoning in butterfly
• Thorn of bougainvillea and the tendril of cucurbits
  • Both arise from the axillary position
  • Serve different functions

Analogous Organs

• Analogous organs have similar functions but are different in their structure and origin.
• These are the results of convergent evolution.
• The presence of analogous organs indicates a similar adaptation by unrelated groups through modification or evolution of different parts.

Examples of Analogous Organs:

• Wings of insects and wings of birds
• Pectoral fins of sharks and flippers of dolphins
• Eye of octopus and eye of a cat.