Do Mendel's principles of genetics apply to all organisms?

• A. They apply only to peas
• B. They apply to all organisms
• C. They apply only to animals
• D. They do not apply to organisms with sex chromosomes

Answer: (B)

The idea being tested is that Mendel’s principles describe universal patterns of inheritance that come from the basic way genes are passed on during reproduction. In most sexually reproducing organisms, genes exist in pairs in the diploid state, and during gamete formation these gene copies separate so that each gamete carries one allele from each gene (segregation). When gametes fuse at fertilization, offspring inherit alleles from both parents, producing predictable genotype and phenotype ratios for simple traits. Because the cellular processes of meiosis and fertilization are shared across many organisms, Mendel’s two main ideas—the segregation of alleles and the independent assortment of genes on different chromosomes—apply broadly, not just in peas. That’s why this statement is considered true in a general sense: the same inheritance patterns underlie how traits are transmitted in a wide range of species, even though real-world details can add complexity. It’s good to keep in mind there are exceptions and refinements—sex-linked patterns, polygenic traits, gene linkage, and non-Mendelian inheritance can alter expected ratios—but the foundational concepts described by Mendel provide a universal framework for understanding inheritance across organisms.