Define homologous organs,recapitulation theory,and fossils.

(N/A) $1$. Homologous Organs: These are organs that share a common evolutionary origin and basic structural plan but may perform different functions in different organisms. For example,the forelimbs of whales,bats,cheetahs,and humans share the same anatomical structure (humerus,radius,ulna,carpals,metacarpals,and phalanges) but are adapted for different functions like swimming,flying,running,and grasping.
$2$. Recapitulation Theory (Biogenetic Law): Proposed by Ernst Haeckel,this theory states that 'ontogeny repeats phylogeny'. It suggests that the embryonic development of an individual organism (ontogeny) reflects the evolutionary history of its species (phylogeny).
$3$. Fossils: These are the preserved remains,impressions,or traces of organisms that lived in the past. They are found in sedimentary rocks and provide direct evidence of evolutionary changes over geological time.