Which of the following is true about dominant and recessive alleles?

Dominant alleles are characterized by their ability to mask the expression of recessive alleles in an organism's phenotype. When an individual carries at least one dominant allele for a trait, the phenotype will reflect that dominant allele rather than the recessive one. This means that the traits associated with dominant alleles are visually expressed more prominently compared to those associated with recessive alleles, which require two copies (one from each parent) to manifest in the phenotype.

In contrast, recessive alleles only exert their influence when present in a homozygous condition, meaning that an individual must inherit two recessive alleles for the trait they code for to be expressed. This is the foundation of Mendelian genetics, where the relationship between dominant and recessive alleles determines the inherited characteristics of organisms. Understanding this dominance hierarchy is crucial for predicting phenotypes based on genotype.