If an inherited disorder is inherited as a simple recessive trait, what will express the phenotype for the disorder?

If an inherited disorder is inherited as a simple recessive trait, what will express the phenotype for the disorder?

• A. Heterozygous dominant
• B. Homozygous recessive
• C. Homozygous dominant
• D. Heterozygous recessive

Answer: (B)

In the context of simple recessive inheritance, for a phenotype to be expressed, an individual must possess two copies of the recessive allele. This means that the individual must be homozygous recessive, which designates that both alleles at a particular locus are the recessive form associated with the disorder. In genetic terms, the alleles can be represented as 'A' for the dominant trait and 'a' for the recessive trait. Therefore, only individuals with the genotype 'aa' will exhibit the characteristics of the inherited disorder. In contrast, individuals who are homozygous dominant ('AA') or heterozygous ('Aa') will display the dominant phenotype and not express the disorder. This understanding highlights why homozygous recessive is the only genotype that will show the phenotype corresponding to the inherited disorder within the framework of simple recessive traits.

In the context of simple recessive inheritance, for a phenotype to be expressed, an individual must possess two copies of the recessive allele. This means that the individual must be homozygous recessive, which designates that both alleles at a particular locus are the recessive form associated with the disorder.

In genetic terms, the alleles can be represented as 'A' for the dominant trait and 'a' for the recessive trait. Therefore, only individuals with the genotype 'aa' will exhibit the characteristics of the inherited disorder. In contrast, individuals who are homozygous dominant ('AA') or heterozygous ('Aa') will display the dominant phenotype and not express the disorder.

This understanding highlights why homozygous recessive is the only genotype that will show the phenotype corresponding to the inherited disorder within the framework of simple recessive traits.