Which principle states that dominant allele determines the phenotype in a heterozygote?

• A. Law of Segregation
• B. Principle of Dominance
• C. Law of Independent Assortment
• D. Non-Mendelian inheritance

Answer: (B)

The principle of dominance explains that in a heterozygote, the dominant allele masks the recessive allele and determines the phenotype. When an organism has a genotype like Aa, the dominant allele A dictates the phenotype, while the recessive allele a only affects appearance if paired with another a (as in aa). The other concepts describe how alleles are inherited and distributed, not which allele controls appearance in a heterozygote: the law of segregation covers how alleles separate into gametes, the law of independent assortment covers how different genes assort independently, and non-Mendelian inheritance refers to patterns that don’t follow Mendelian rules.