IGCSE Biology glossary
Gene
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
A length of DNA that codes for a protein (the unit of inheritance passed from parent to offspring).
What to include in an exam answer
The Extended-level paying point is that a gene is a length of DNA that codes for a protein. Do not confuse a gene with an allele: an allele is a version of a gene. Students also lose marks writing that genes are 'found on chromosomes' as the whole answer, without saying what a gene actually is. Appears across inheritance, variation and biotechnology topics.
Example in context
Defining the term: 'A gene is a length of DNA that codes for a particular protein, and different forms of the same gene are called alleles.'
Related syllabus topic
Inheritance