Assertion (A): Polymorphism in DNA sequence is the basis of genetic mapping of human genome as well as of DNA fingerprinting.
Reason (R): Polymorphism (variation at genetic level) does not arise due to mutations.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A is true but R is false.
Assertion (A): Polymorphism in DNA sequence is the basis of genetic mapping of human genome as well as of DNA fingerprinting. — True. DNA polymorphism means variation at the genetic level: small differences in DNA sequence between individuals. These differences are what genetic mapping of the human genome and DNA fingerprinting are built on.
Reason (R): Polymorphism (variation at genetic level) does not arise due to mutations. — False. Polymorphism does arise due to mutations. New mutations appear in somatic cells or germ cells. A germ-cell mutation that does not harm the ability to have offspring can spread through the population and becomes a variation. R denies this, so it is false.
Since A is true and R is false, Option (4) is the answer.
NCERT Extract:
DNA Fingerprinting – “… As polymorphism in DNA sequence is the basis of genetic mapping of human genome as well as of DNA fingerprinting, it is essential that we understand what DNA polymorphism means in simple terms. Polymorphism (variation at genetic level) arises due to mutations. … New mutations may arise in an individual either in somatic cells or in the germ cells (cells that generate gametes in sexually reproducing organisms).”