Explain the concept of half life

Explanation:

Half-life is defined as the time it takes for one-half of a radioactive element to decay into a daughter isotope. As radioactive isotopes of elements decay, they lose their radioactivity and become a brand new element known as a daughter isotope.

The correct answer would be XRXr.

In humans, X and Y are the sex chromosomes which determine the gender of the person.

The males are heterozygous, that is, they are XY whereas the females are homozygous for the X chromosome, that is, XX.

The x-linked recessive disorder is the one in which the alleles for the disease are carried by the X chromosome. As females are XX, thus, both X chromosome must carry the recessive allele in order to produce the phenotype.

Therefore, the genotype of the carrier of a recessive disease must be heterozygous in nature.  

For example, the carrier of the recessive disease would carry one recessive allele and one dominant allele in its genotype.

Thus, the genotype of the X-linked recessive disease would be XRXr.