Here's why:
* Alleles are alternative forms of a gene.
* Genes contain instructions for building and maintaining an organism.
* Phenotype refers to the observable characteristics of an organism, like its physical appearance, behavior, and biochemical properties.
Expressed alleles are those whose instructions are actually used by the cell to create a protein or other functional product that influences the organism's phenotype. This means that the allele's instructions are translated into a functional product.
Here are some important points about expressed alleles:
* Dominant alleles always express their trait, even if only one copy is present.
* Recessive alleles only express their trait if two copies are present.
* Codominant alleles both express their traits equally.
* Incomplete dominance results in a blending of the traits from the two alleles.
In summary: Expressed alleles are the ones that make a difference in how an organism looks, behaves, or functions. They are the alleles whose instructions are actually used by the cell to create a functional product.
