The form of a gene that has no impact on a trait in the heterozygous state is called a recessive allele.

Here's a breakdown:

* Allele: A specific version of a gene.

* Heterozygous: Having two different alleles for a gene.

* Recessive: An allele that only expresses its trait when two copies of it are present (homozygous recessive).

Example:

* Gene: Eye color

* Alleles: Brown (B) and blue (b)

* Heterozygous: Bb (brown eyes)

* Recessive: b (blue eyes)

In this example, the brown allele (B) is dominant, meaning it masks the expression of the blue allele (b) in the heterozygous state. A person with the genotype Bb will have brown eyes because the dominant brown allele overshadows the recessive blue allele. Only someone with two copies of the blue allele (bb) will have blue eyes.