Question

‘Ontogeny recapitulates phylogeny’ . This is the
A) Pauling law
B) Hardy-weinberg law
C) biogenetic law
D) Thomas law

Answer 1

Hint: According to this hypothesis, almost every higher animal shares common ancestry because they show the similarity in early embryological structure but when they mature they can be easily distinguished .

Complete answer:
There is much evidence which helps in understanding the process of evolution and among them , one is embryological evidence.
1) Early development in triploblastic organisms (Platyhelminthes to mammals) is similar . That means after fertilisation zygote is formed and due to cleavage in zygote, lastual is formed which further give rise to Gastrula ad this gastrula will form the three germ layer (Ectoderm, mesoderm and endoderm).
Same early development in all triploblastic animals gives a clue that these highly evolved organisms originated from the less evolved organism.
2) Early embryo development in vertebrates:
When we compare the embryos of fishes, amphibians, reptiles, birds and mammals , we will find about similar structures in the early embryonic development. Like all the vertebrate embryos in the early stages it has a tail , gill slits, eyes and ear buds .

Biogenetic law or Recapitulation theory or embryological parallelism given by Ernst Haeckel . According to this theory ‘Ontogeny recapitulates phylogeny ’ .
Ontogeny means development of embryos from zygote to matured organisms .
Phylogeny means the relationship between the organisms in the evolutionary history .
 Developmental stages of embryo of all different organisms (like human beings, chicken, frog) of distantly related groups show remarkable similarity between those stages. So it is very difficult to distinguish between the developing embryos at a very early stage.
It shows that a very basic level of development shares a similar common ancestral pattern . As the time goes by , they mature into completely different organisms.

Hence the correct answer is OPTION(C)

Note: Recapitulation theory: this theory was given by Von Bear . He said that general structure develops first followed by the special structures. General structure (which is common in all vertebrates embryo) include brain, spinal cord, axial skeleton while special structure includes feathers in case of birds, hairs in case of mammals.
Later this theory was modified by Earnst Haeckal and called as Biogenetic law.