What principle states that some alleles are dominant while others are recessive?

The principle that states some alleles are dominant while others are recessive is known as the Principle of Dominance. This principle, first described by Gregor Mendel through his experiments with pea plants, explains that in a heterozygous individual (one with two different alleles for a trait), the dominant allele will mask the expression of the recessive allele. For instance, if one allele codes for a trait like purple flower color and another for white, the plant will exhibit the purple color, demonstrating dominance.

Understanding this principle is crucial for interpreting genetic inheritance patterns, as it underlies the concept of genotype and phenotype relationships in organisms. The other principles mentioned—like the Law of Segregation and the Law of Independent Assortment—focus on different aspects of genetic inheritance rather than the dominance of alleles over one another. The chromosomal theory pertains to the structures and behaviors of chromosomes during cell division, further illustrating the diverse foundational principles that govern Mendelian genetics.