What is the effect of a dominant gene on a recessive gene?

• A. The recessive gene is enhanced
• B. The recessive gene is masked
• C. They both express equally
• D. They compete for expression

Answer: (B)

A dominant gene has the capability to overshadow the presence of a recessive gene. This masking effect occurs because dominant alleles produce functional proteins or traits, while recessive alleles do not manifest unless two copies are present. When an individual inherits one dominant allele and one recessive allele for a particular trait, the dominant trait is expressed, effectively hiding the effect of the recessive allele. This is fundamental to Mendelian genetics, which illustrates that dominant alleles will always express their traits when paired with recessive ones, leading to the coincidence of dominant traits appearing in the phenotype despite the presence of recessive alleles.