What are homologous and analogous organs? Give examples.

Homologous organs are body parts that look different and do different jobs but share the same underlying bone structure, showing a common ancestor — like a human arm, a bird's wing, and a whale's flipper. Analogous organs do the same job (like flying) but are built completely differently, like a bird's wing and a butterfly's wing — they evolved independently.

Homologous organs: These have the same basic structural plan and origin (share a common ancestor) but perform different functions. They indicate divergent evolution. Examples: 1. Forelimbs of humans (used for grasping), forelimbs of birds (modified as wings for flying), forelimbs of whales (modified as flippers for swimming) — all have the same pentadactyl (five-digit) bone structure. 2. Thorns of Bougainvillea and tendrils of Cucurbita — both are modified branches. Analogous organs: These have different basic structures and origins but perform similar functions. They indicate convergent evolution. Examples: 1. Wings of birds and wings of insects — bird wings have bones and feathers, insect wings are membranous extensions of the exoskeleton. Both are used for flying. 2. Fins of fish and flippers of whales — fish fins are supported by fin rays, whale flippers have a pentadactyl skeletal structure. Both are used for swimming.