Florida Biology EOC Practice Test

An organism with a dominant phenotype consistently expresses a dominant trait because the dominant allele masks the effects of any recessive alleles present in its genotype. According to Mendelian genetics, when an organism has at least one dominant allele, the dominant trait will be the one that is observed in the phenotype.

For example, if the dominant trait is represented by allele "A" and the recessive trait by allele "a," then both the homozygous dominant genotype (AA) and the heterozygous genotype (Aa) will lead to the same observable trait—expressing the dominant phenotype. This is why the assertion that it will express a dominant trait regardless of the genotype is accurate in the context of dominant and recessive alleles.

In contrast, organisms expressing recessive traits would need to have two copies of the recessive allele (aa). Environmental factors can also influence phenotypic expression, but this is separate from the intrinsic genetic dominance of traits. Therefore, the correct understanding aligns with how dominant alleles work biologically in determining observable characteristics.