Answer:
A dominant allele is one of two or more versions of a gene that, when inherited, masks the effect of another allele or alleles. In genetics, alleles are different forms of a gene that arise by mutation and are found at the same place on a chromosome. When an organism has two different alleles for a particular trait, the allele that is expressed and determines the phenotype (observable characteristics) of the organism is called the dominant allele. The allele that is masked and does not affect the phenotype in the presence of a dominant allele is called the recessive allele.
Explanation:
For example, in pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p). This means that plants with the genotypes PP (homozygous dominant) or Pp (heterozygous) will have purple flowers, while only plants with the genotype pp (homozygous recessive) will have white flowers. The presence of at least one P allele is enough to determine the purple flower phenotype, making it the dominant allele.
