Biology Inheritance / Variation & Genetics SZABMU 2023
PMDC Verified Question 47 of 94
When a haemophilic carrier woman marries a haemophilic man, who among her offspring's may be affected?
A
All her children
B
All her daughters
C
Half of her daughters and all sons
D
Half of her sons and half of her daughters
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Half of her sons and half of her daughters
Concept:

Haemophilia is an X-linked recessive disorder. We track the mutated \(X^h\) allele through a Punnett square.

Solution:

  • Mother's genotype: Carrier (\(X^H X^h\))
  • Father's genotype: Affected (\(X^h Y\))
  • The cross yields the following four possibilities:
  • Daughters: \(X^H X^h\) (Carrier, 50%) and \(X^h X^h\) (Affected, 50%).
  • Sons: \(X^H Y\) (Normal, 50%) and \(X^h Y\) (Affected, 50%).
  • Therefore, exactly half of her sons and half of her daughters will be affected by the disorder.


Why other options are incorrect:

  • Options A, B, and C fail to account for the mother's dominant, healthy \(X^H\) allele, which protects 50% of the offspring.

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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