Question

When a specific genotype for one gene prevents the expression of a separate gene, the one that masks another is said to be _________.

1) dominant
2) recessive
3) homozygous
4) heterozygous

Answer 1

The genotype that prevents the expression of a separate gene by masking it is known as a dominant. This occurs when a dominant allele covers the effects of a recessive allele in a heterozygous pairing.

Step-by-step explanation:

When a specific genotype for one gene prevents the expression of a separate gene, the one that masks another is said to be dominant. In genetic terms, the trait that is seen in the phenotype, regardless of whether the genotype is homozygous dominant (AA) or heterozygous (Aa), is due to the dominant allele. A dominant allele will always mask the expression of a recessive allele when they are together in a heterozygous state (Aa).

A classic example of dominance is blood type, where the allele for blood type A (an allele that is dominant) will mask the expression of blood type O (which is recessive) when they occur together in a heterozygote (Aa). In such cases, an individual will exhibit blood type A as the dominant trait, and blood type O only if both alleles are recessive (oo).

It is important to note the distinction between dominance and recessive interactions, as well as the different possible combinations an individual can have: homozygous dominant (AA), heterozygous (Aa), and homozygous recessive (aa).