Biology Inheritance / Variation & Genetics KMU 2024
PMDC Verified Question 10 of 94
Which is true for an X-linked dominant trait?
A
All female offspring of the affected father will be affected
B
Half of the female offsprings of the affected father will be affected
C
No male offspring of an affected mother will be affected
D
No female offspring of the affected father will be affected
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: All female offspring of the affected father will be affected
Concept:

In X-linked dominant inheritance, a single copy of the mutant allele is sufficient to cause the disorder.

Solution:

  • An affected father has the genotype \(X^D Y\) (where D is the dominant disease allele).
  • He passes his Y chromosome to all his sons, who will therefore be completely unaffected.
  • He passes his mutant \(X^D\) chromosome to 100% of his daughters.
  • Because the trait is dominant, receiving just one copy of \(X^D\) guarantees the disease. Thus, all female offspring of the affected father will be affected.


Why other options are incorrect:

  • Half of female offspring: Incorrect, all daughters receive his X chromosome.
  • No male offspring of affected mother: Incorrect, an affected mother (\(X^D X^d\)) has a 50% chance of passing it to her sons.

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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