Final answer:
Dominance in genetics refers to the relationship where one allele masks the effects of another allele for the same gene, determining the organism's phenotype.
Step-by-step explanation:
Dominance is a genetic relationship between two alleles of the same gene.
In the context of genetics, when we talk about dominance, we are referring to how certain alleles (variations of a gene) interact with each other to determine the phenotype of an organism. Each gene may have multiple alleles, but typically, a diploid organism has two alleles for each gene, one from each parent. If an organism possesses two different alleles for a gene, the allele that masks the effect of the other is considered dominant, while the one whose effect is masked is recessive.
This concept is integral to understanding Mendelian inheritance, where traits are transmitted from parents to offspring through genes. For example, in pea plants, the allele for purple flowers is dominant over the allele for white flowers. Therefore, a plant with one purple-flower allele and one white-flower allele will still show the purple flower phenotype. The recessive allele (white flower) can only be expressed if both alleles are the recessive form.