What does it mean to be homozygous for a trait?

Being homozygous for a trait means that an individual has two copies of the same allele for a specific gene. This can occur when both alleles are either dominant or recessive, leading to a uniform genetic expression for that trait. For example, if a plant has two alleles for purple flowers, both being the purple allele, it is considered homozygous. This is important in genetics because when a cross occurs with a homozygous individual, the offspring will inherit the same allele from that parent, potentially leading to predictable outcomes in traits.

Homozygosity contrasts with heterozygosity, where two different alleles are present for a trait. This distinction is critical in understanding inheritance patterns and the concept of genotype, which profoundly influences phenotypic outcomes in organisms.