Question

For the trait hemophilia, individuals can inherit dominant alleles (normal blood clotting) or recessive alleles (hemophilia—cannot clot blood). Heterozygousindividuals are carriers for this trait, meaning they have the recessive allele in their cells, but do not express hemophilia. Which of the following BEST explains why these individuals do not express the trait?

Group of answer choices

One of a female’s X chromosomes is inactivated in every cell as dosage compensation.

Females are the heterogametic sex in humans, while females are the homogametic sex.

Expression of hemophilia exhibits phenotypic plasticity.

The Y chromosome does not contain essential genes for life.

Answer 1

The best explanation for why the hemophilic heterozygous individuals to not show the trait is-

One of a female’s X chromosomes is inactivated in every cell as dosage compensation.

Explanation- Being an X-linked recessive disorder, females are generally not affected, although they can be carriers of this disorder.

The cause of expression of haemophilia disease only in homozygous recessive condition and not in heterozygous individuals is dosage compensation. It involves skewed inactivation of the X chromosome leading to predominant expression of the mutated allele as a result of a preferential inactivation of the X chromosome with the wild-type .