Question

Sol.(a) [Key Concept: Point Mutation — Definition] Point mutation involves a CHANGE IN A SINGLE BASE PAIR of DNA. This includes: substitutions (one base replaced by another — transitions: purine↔︎purine or pyrimidine↔︎pyrimidine; transversions: purine↔︎pyrimidine), insertions of one base pair, or deletions of one base pair. Large-scale duplications, deletions, or insertions are chromosomal mutations, not point mutations. Sickle cell anaemia is caused by a classic point mutation (GAG→GTG/GUG substitution).