Question

Which of the following is the source of polymorphism in DNA?

• A. Crossing over
• B. Inbreeding
• C. Mutation
• D. Both a and b

Answer 1

The correct option is C Mutation

Polymorphism is the variation in the genetic makeup of individuals of a particular species in a population. New mutations may arise in a person’s cell. Since those mutations usually occur in the non-coding sequences, hence, the reproductive ability of the individual is not hampered. Mutations occurring in the germ cells, if not affecting an individual's ability to have offspring, can get transmitted to their offspring. This can further spread to the other members of the population in subsequent generations. These mutations keep on accumulating generation after generation to give rise to different traits in individuals. Once more than one allele variant occurs in a population with frequency greater than 0.01, it is considered as DNA polymorphism.
Inbreeding is the mating of closely related individuals. It leads to formation of pure lines.
Crossing over is the interchange of chromosomal parts between non-sister chromatids of homologous chromosomes during meiosis. It helps in genetic recombination.