Question

The major/ ultimate source of variations are

• A. Polyploidy
• B. Mutations
• C. Chromosome aberrations
• D. Segregation

Answer 1

Answer: (B)

Mutations

Ultimate source of variation is MUTATION and nothing else. Mutations are mistakes that occur in DNA sequence of genome:

• Point mutation e.g. nonsense and missense mutations
  
• Frame-shift mutation e.g. insertion or deletion mutations
  

Any change in genetic DNA will be translated into a defect in the corresponding protein. Thus mutation is responsible for appearance of a phenotypic variation. Such a variation may help the organisms carrying the new variation to survive better. If it produces more progeny the variation will appear in more members. Variations which provide adaptive advantage get selected by nature, thus help organisms to evolve.

So, the correct answer is 'Mutations'.