Biology Genetics Practice Test 2026 - Free Genetics Practice Questions and Study Guide

Genotype is the genetic makeup—the exact set of alleles an organism carries at the genes being considered. It determines what traits could potentially be expressed, while the actual trait you see (the phenotype) also depends on environmental factors and how those alleles interact. For example, with a gene that has dominant and recessive variants, the genotype (such as having at least one dominant allele) helps predict the possibility of showing the dominant trait, though environment can influence the final appearance. In contrast, phenotype is the outward trait, inheritance is about passing genes to offspring, and probability is a measure of how likely certain genetic outcomes are.