Change in the base sequence within a gene is called

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Correct — A, Mutation. A gene is a stretch of DNA read as a sequence of bases (A, T, G, C). A mutation is a heritable change in that base sequence — a substitution, insertion or deletion of one or more bases. Such changes can alter the protein a gene codes for and are the ultimate source of new genetic variation.

Why the other options are wrong — (b) Cloning produces genetically identical copies of a gene, cell or organism; it copies the existing base sequence rather than changing it.  (c) Fusion refers to joining two cells, protoplasts or nuclei into one; it combines whole genomes but does not, by definition, alter the base sequence within a gene.  (d) Breeding is controlled reproduction to combine desirable traits across generations; it reshuffles existing genes rather than changing the base sequence of a single gene.

Concept: DNA stores information as an ordered sequence of four bases; a gene is a functional segment of this sequence. When that order is altered — by substitution, insertion or deletion of bases — the change is a mutation. Mutations may be silent, may change a protein, or may be harmful/beneficial, and they are the raw material on which natural selection acts.

State PCS 2020 Q89 — Science & Technology PYQ with Answer

State PCS 2020 Q89 — Science & Technology PYQ with Answer