Biology Inheritance / Variation & Genetics ETEA 2022
PMDC Verified Question 67 of 94
What are the chances that the daughter of a normal man and a heterozygous female will have hemophilia?
A
75%
B
5%
C
25%
D
0%
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 0%
Concept:

Hemophilia is X-linked recessive. A female must inherit two defective X alleles to express the disease.

Solution:

  • Father's genotype: Normal man = \(X^H Y\).
  • Mother's genotype: Heterozygous female (carrier) = \(X^H X^h\).
  • A daughter must inherit one X chromosome from her mother and her second X chromosome from her father.
  • Since the father is perfectly normal, he can only pass on a healthy, dominant \(X^H\) allele to his daughters.
  • Because every daughter receives at least one dominant \(X^H\) allele, none can be homozygous recessive (\(X^h X^h\)).
  • Therefore, the chance of a daughter having hemophilia is exactly 0%.


Why other options are incorrect:

  • The daughters have a 50% chance of being carriers (\(X^H X^h\)), but zero chance of being afflicted with the disease.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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