what is the best evidence to prove that irene was heterozygous for hemophilia?\no elizabeth is not a carrier…

what is the best evidence to prove that irene was heterozygous for hemophilia?\no elizabeth is not a carrier for the trait.\no tatiana carried the recessive allele.\no her brother has hemophilia and her sister is a carrier.\no two of her sons have hemophilia and one does not.

what is the best evidence to prove that irene was heterozygous for hemophilia?\no elizabeth is not a carrier for the trait.\no tatiana carried the recessive allele.\no her brother has hemophilia and her sister is a carrier.\no 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. Males have one X and one Y chromosome (XY), and females have two X chromosomes (XX). A heterozygous female has one normal and one mutant allele on her X - chromosomes.

Step2: Analyze male offspring inheritance

When a woman has sons, she passes on her X - chromosome to them. If she is heterozygous for hemophilia, there is a 50% chance of passing on the mutant allele and a 50% chance of passing on the normal allele. If two of her sons have hemophilia (received the mutant allele) and one does not (received the normal allele), it is strong evidence that she is heterozygous.

Step3: Evaluate other options

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