IGCSE Biology glossary
Genotype
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 genetic make-up of an organism. The combination of alleles it carries for a characteristic, written as letters (e.g. RR, Rr or rr).
What to include in an exam answer
Always paired with phenotype in exam questions. State genotypes with defined letters and write the phenotype in words. Losing the definition marks here is pure carelessness. These are reliable marks if learned.
Example in context
Stating a cross result: 'The genotype of the heterozygous tall plant is Tt, carrying one dominant and one recessive allele.'
Related syllabus topic
Inheritance