What is the basic unit of heredity?

• A. Chromosome
• B. Gene (DNA sequence)
• C. Genome
• D. Allele

Answer: (B)

A gene is the basic unit of heredity, a specific sequence of DNA that carries the instructions to make a product—usually a protein or RNA—that influences a trait. Genes encode the heritable information passed from parents to offspring and expressed in the organism. A chromosome is a larger structure that contains many genes lined up along its length and serves as the physical carrier of genetic material during cell division. The genome refers to the entire set of genetic material in an organism, including all genes and noncoding regions. An allele is a variant form of a gene that can lead to differences in a trait. Because heredity hinges on these discrete units that transmit trait information, the gene best fits as the basic unit.