Heterozygous refers to an organism that has two different alleles for a specific gene. Alleles are variations of a gene that can produce different traits. For example, in the case of the gene for flower color in pea plants, a plant can be heterozygous if it has one allele for purple flowers and another for white flowers. In genetics, being heterozygous can influence how traits are expressed. If one allele is dominant and the other is recessive, the dominant trait will typically be the one that is visible. This concept is important in understanding inheritance patterns and is a key principle in the study of Mendelian genetics.