* Heterozygous means having two different alleles for a particular gene.
* Recessive means an allele only expresses its trait when two copies of it are present.
If an organism is heterozygous, it means it has one dominant allele and one recessive allele. The dominant allele will mask the expression of the recessive allele, so the organism will display the trait associated with the dominant allele.
Example:
* Let's say "B" represents the dominant allele for brown eyes and "b" represents the recessive allele for blue eyes.
* A person with the genotype "Bb" would have brown eyes because the "B" allele is dominant.
* They are heterozygous for eye color, but they are not recessive because the dominant allele is being expressed.
To be truly recessive, an organism needs two copies of the recessive allele (bb). In this case, the dominant allele is not present, so the recessive trait is expressed.
