Assistant Laboratory Animal Technician (ALAT) Practice Exam

In a pair of genes, which one is less easily expressed?

1. Recessive

2. Codominant

3. Dominant

4. Incomplete dominant

The correct answer is: Recessive

A recessive gene is less easily expressed because its phenotypic effect is masked when a dominant allele is present. This means that for a recessive gene to manifest in an organism, it must be present in a homozygous form, meaning both alleles must be recessive. In contrast, dominant genes only require one dominant allele to express their trait, making them more readily observable in the phenotype. In the context of codominant and incomplete dominant traits, these gene types also exhibit expression differently. Codominant alleles produce distinct phenotypic effects in the presence of one another, while incomplete dominance results in a blended phenotype. However, regardless of these scenarios, the key characteristic of recessive alleles is that they remain unexpressed unless paired with another recessive allele, thereby establishing their status as the least easily expressed among the provided choices.