what is the best evidence to prove that irene was heterozygous for hemophilia? elizabeth is not a carrier…

what is the best evidence to prove that irene was heterozygous for hemophilia? elizabeth is not a carrier for the trait. tatiana carried the recessive allele. her brother has hemophilia and her sister is a carrier. two of her sons have hemophilia and one does not.

what is the best evidence to prove that irene was heterozygous for hemophilia? elizabeth is not a carrier for the trait. tatiana carried the recessive allele. her brother has hemophilia and her sister is a carrier. two of her sons have hemophilia and one does not.

Answer

Answer:

D. Two of her sons have hemophilia and one does not.

Explanation:

Step1: Understand hemophilia inheritance

Hemophilia is an X - linked recessive disorder. Females have two X chromosomes (XX), and males have one X and one Y chromosome (XY). A heterozygous female has one normal and one mutant allele on her X - chromosomes.

Step2: Analyze offspring genotypes

If a female is heterozygous for hemophilia (X^HX^h), when she has sons, they inherit their X - chromosome from her. Sons with the X^h allele will have hemophilia, and sons with the X^H allele will not. If two of her sons have hemophilia (X^hY) and one does not (X^HY), it indicates that she passed on both the normal and the mutant X - chromosome alleles, which means she is heterozygous.

Step3: Rule out other options

  • Option A: Elizabeth not being a carrier has no direct bearing on Irene's genotype.
  • Option B: Tatiana carrying the recessive allele does not provide evidence about Irene's genotype.
  • Option C: Her brother having hemophilia and sister being a carrier does not as directly prove Irene's heterozygosity as the evidence from her own sons.