What does it mean to be homozygous?

• A. Having two different alleles for a specific gene
• B. Having two identical alleles for a specific gene
• C. Having no alleles for a specific gene
• D. Having multiple alleles for a specific gene

Answer: (B)

To be homozygous means that an individual has two identical alleles for a specific gene. This can occur in various contexts of genetics, such as when both alleles are dominant or both are recessive. When an individual is homozygous for a trait, the genetic expression for that trait will be consistent, as there is no variation in the alleles present for that gene. For example, if a plant has two alleles for flower color that are both red, it is considered homozygous for that trait. This genetic uniformity can affect how traits are passed down to offspring, including the predictability of inherited characteristics.

In contrast, having two different alleles for a specific gene characterizes a heterozygous condition, while the absence of alleles does not align with the definition of being homozygous. Similarly, multiple alleles for a gene indicate more than two variations exist within a population but do not relate directly to an individual being classified as homozygous for a specific gene.