IGCSE Coordinated Science Vocabulary Practice Test 2026 – The All-in-One Guide to Exam Success!

Genotype describes the genetic makeup for a specific gene pair. In diploid organisms, you have two alleles at a gene locus—one inherited from each parent—and the genotype is the actual combination of those alleles, such as two copies of the same allele or two different alleles. This combination sets up what traits can be inherited. The observable trait, which may also be influenced by the environment, is called the phenotype. An allele is simply one variant of the gene, a piece of the puzzle that forms the genotype but doesn’t by itself describe the full genetic makeup. A food web has no relation to the genetic makeup of a gene pair. For example, with a color gene that has alleles R and r, the possible genotypes are RR, Rr, and rr, and the phenotype depends on how those alleles interact.