Questions: Which type of allele is sometimes referred to as a loss-of-function gene? Recessive allele Incomplete allele Dominant allele

The answer is the first one (or A): Recessive allele.

Explanation for each option:

1. Recessive allele: This is correct. A recessive allele is often referred to as a loss-of-function gene because it typically results in a non-functional protein or no protein at all. For a recessive trait to be expressed, an individual must inherit two copies of the recessive allele, one from each parent. In the presence of a dominant allele, the recessive allele's effect is masked.

2. Incomplete allele: This is incorrect. Incomplete dominance refers to a situation where neither allele is completely dominant over the other, resulting in a phenotype that is a blend of both alleles. It does not specifically refer to a loss-of-function gene.

3. Dominant allele: This is incorrect. A dominant allele is one that expresses its trait even when only one copy is present. It typically produces a functional protein that masks the effect of a recessive allele. Dominant alleles are not generally referred to as loss-of-function genes.

Summary: The type of allele sometimes referred to as a loss-of-function gene is the recessive allele.