NEET BIOLOGY

Detailed explanation-1: -They all have folds called gill pouches in the neck region. In fish, these folds develop into gills. Although adult chickens and humans do not have gills, the similarities in their embryos suggest that these organisms are at least distantly related.

Detailed explanation-2: -Comparative embryology is the study of the similarities and differences in the embryos of different species. Similarities in embryos are evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails. Most vertebrates, except for fish, lose their gill slits by adulthood.

Detailed explanation-3: -Similar structures are present in the embryos of fish, chickens, and rabbits. In fish, these structures develop into gills, but in chickens and rabbits, they either disappear or develop into other body parts later in embryonic development. The three species have a common ancestor with these embryonic structures.

Detailed explanation-4: -For example, fish embryos and human embryos both have gill slits. In fish they develop into gills, but in humans they disappear before birth.

Detailed explanation-5: -In the embryos of all vertebrates, the presence of gill slits supports the theory of recapitulation (repeating the early stages of embryogenesis in earlier evolved animals.)