Definition: One of Mendel's Laws of Inheritance. This law states an organism has two different alleles for a trait and the allele that is expressed in the phenotype, masking the expression of the other allele is said
to be dominant. The allele whose expression is masked is said to be recessive.
Example: Purple flowers are dominant over white. Purple is dominant; white recessive. When a purple
flowering plant is crossed with a white flowering plant, all off-spring have purple flowers.