IGCSE Biology glossary
Natural selection
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
The process by which individuals with variation better suited to the environment are more likely to survive and reproduce, passing on their alleles, so the favourable feature becomes more common over generations.
What to include in an exam answer
The 6-mark version is formulaic: variation exists → competition/selection pressure → best adapted survive → reproduce → pass on alleles → frequency increases over generations. Antibiotic resistance is the most commonly examined context.
Example in context
For antibiotic resistance: 'Resistant bacteria survive the antibiotic, reproduce and pass on the resistance allele, so over generations the resistant type becomes more common. This is natural selection.'
Related syllabus topic
Variation & selection