Question

A baby has been born with a small tail. It is a case exhibiting
A. Retrogressive evolution
B. Mutation
C. Atavism
D. Metamorphosis

Answer 1

Hint: Evolutionary biology involves the study of history of different life forms on the earth. It involves organic evolution which is the formation of newer types of organisms from the pre-existing organisms through modifications.

Complete answer: Retrogressive evolution can be defined as the formation of simpler and less elaborate forms of organisms from complex organisms. This process is reverse to progressive evolution which involves the formation of more complex, elaborate and specialized structures from simple structures.
Mutation is defined as the sudden inheritable discontinuous variations that will appear in the organisms due to permanent change in their genotypes. Hugo de Vries proposed the mutation theory of evolution in his book “The Mutation Theory” published in 1903. Mutations are of three types:
Genomic mutation- These are changes in the number of chromosomes. These are of two types- polyploidy and aneuploidy.
Chromosomal mutations involve changes in the number and arrangement of genes in the chromosomes. These are called chromosomal aberrations.
Gene mutations are variations either in the form or expression of genes.
Metamorphosis is defined as the transformation of an immature larval individual into a sexually mature reproducing adult. The adults formed are of very different forms, structure and different habits of life. It is commonly seen in insects. Insects display four types of metamorphosis-
No-metamorphosis or ametabolous development
Incomplete metamorphosis or hemimetabolous development
Gradual metamorphosis or paurometabolous development
Complete metamorphosis or holometabolous development
Hype meta bolous
The reappearance of the ancestral features in any individual for example, tail in a baby, longer canine in man, hair on face and body, etc. is atavism. Other examples of atavism are long arm and abdominal nipples, separation of splint bones in horse, etc.
So, the correct answer is “Option C”.

Note: Atavism is one of the several pieces of evidence that convince that the modern diverse forms of the organisms have arisen by evolution from more ancient forms. Other evidence for this are evidence from connecting links, embryology, paleontology, biogeography, cytology and genetics, etc.