HOSA Human Heredity Practice Test 2026 - Free Human Heredity Practice Questions and Study Guide

The basic unit of heredity is a gene. Genes are segments of DNA that contain the instructions for building and maintaining an organism. They function as the fundamental units that are responsible for the inheritance of traits from parents to offspring. Each gene can influence specific characteristics, such as eye color, height, and susceptibility to certain diseases.

While chromosomes serve as the structures that package and organize genes, they are not the smallest functional unit of heredity. DNA is the overall molecule that carries genetic information, incorporating multiple genes along its length. Alleles are variations of genes that can result in different traits, but they are part of the larger concept of a gene rather than being the fundamental unit themselves. Thus, gene accurately represents the smallest functional unit responsible for heredity.