Cambridge O Level Biology · Syllabus 5090 · Inheritance
Genetic Diagram
What is Genetic Diagram?
A standard way of setting out a cross so that the possible offspring can be predicted. A complete genetic diagram defines the allele symbols, states the phenotype and genotype of each parent, shows the gametes each parent can produce with one allele in each gamete, combines the gametes in a Punnett square or by combination lines, and then states the genotypes and phenotypes of the possible offspring together with the expected ratio. Marks in an examination are distributed across these rows, so a correct Punnett square with no parental genotypes above it scores only part of the total.
This definition is part of the Inheritance chapter in Cambridge O Level Biology.
Last reviewed Syllabus 2026-2028