The law of dominance states that which type of alleles will always be expressed when present?

The law of dominance is a fundamental principle in genetics that explains the relationship between different alleles of a gene. According to this law, when two different alleles are present in an organism (one from each parent), the dominant allele is the one that will be expressed in the phenotype, while the recessive allele will not be expressed unless both alleles are recessive.

In the context of the question, dominant alleles are the types of alleles that will always be expressed when they are present alongside another allele. This means that if an organism has at least one dominant allele, the trait associated with that dominant allele will be visible. This principle is foundational for understanding inheritance patterns in Mendelian genetics and helps to predict how traits will appear in offspring.

Recessive alleles, on the other hand, require two copies (one from each parent) to be expressed. Neutral alleles do not confer a distinct trait, and codominant alleles can both be expressed equally in a heterozygote, rather than one dominating over the other. Thus, the law of dominance clearly identifies dominant alleles as the determining factors in observable traits when paired with other alleles.