Polymorphism in DNA sequence is the basis of:

The correct answer is Option (1) → Genetic mapping of human genome

Polymorphism means variation in the DNA sequence at a place in the genome, which arises through mutations and passes from parents to children. These inherited differences act as markers along the chromosomes.

(1) Genetic mapping of human genome — Correct. In the Human Genome Project, the genetic and physical maps were made using polymorphism of restriction enzyme sites and of repetitive DNA such as microsatellites. The same polymorphism is the basis of DNA fingerprinting.

(2) Chromosomal disorders — Incorrect. These are caused by the absence, excess or wrong arrangement of whole chromosomes, as in Down’s syndrome (an extra chromosome 21). They are not based on small sequence variations.

(3) Co-dominance — Incorrect. In co-dominance both alleles of a gene show their effect together in the hybrid, as in the AB blood group.

(4) Pleiotropy — Incorrect. In pleiotropy a single gene affects several traits, as in phenylketonuria.

NCERT Extract:
DNA Fingerprinting – …