Genetic variation terminology Some types of phenotypic variation arise from heritable changes in the DNA sequence. What is this type of genetic change called?

Introduction / Context:
Variation in populations arises from genetic and environmental sources. When the DNA sequence itself changes, the resulting heritable differences are called mutations. Recognizing this term is foundational for genetics, evolution, and biotechnology.

Given Data / Assumptions:

• The question asks specifically about changes in genetic material (DNA or RNA in some viruses).
• We are distinguishing processes that change genotype versus those that influence phenotype without altering sequence.

Concept / Approach:
A mutation is a permanent alteration in the nucleotide sequence. It can be a base substitution, insertion, deletion, repeat expansion, or larger structural change. Mutations provide raw material for evolution and can be spontaneous or induced.

Step-by-Step Solution:

Verification / Alternative check:
Standard genetics texts define mutation as the heritable change in DNA sequence, distinguishing it from recombination or environmental effects.

Why Other Options Are Wrong:

• Fertilisation: mixes parental genomes; does not create new sequence per se.
• Radiation: a mutagenic cause, not the change itself.
• Sterilisation: eliminates microorganisms; unrelated to genotype.
• Polyploidisation during mitosis: changes chromosome number (genome duplication) but is not typically classified as a “mutation” at the sequence level.

Common Pitfalls:
Confusing mutagenic agents with the mutation event; or conflating recombination/segregation with sequence changes.

Final Answer:
Mutation