Biology Inheritance / Variation & Genetics AJK 2019
PMDC Verified Question 75 of 94
If Sara has blood group O. The genotype of her mother and father is possibly:
A
Bi X BB
B
BB X BB
C
Bi X Bi
D
BB X Bi
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Bi X Bi
Concept:

Blood group O is a recessive trait. To express a recessive phenotype, the individual must be homozygous for the recessive allele.

Solution:

  • Sara has blood group O, meaning her genotype is strictly \(ii\).
  • She must have inherited one recessive \(i\) allele from her mother and one recessive \(i\) allele from her father.
  • Looking at the options, only the cross between two heterozygous individuals (\(I^B i\) x \(I^B i\), denoted here as Bi x Bi) allows both parents to donate an \(i\) allele to the offspring.


Why other options are incorrect:

  • BB x BB and BB x Bi: The homozygous parent (BB) can only pass on a dominant B allele, making it impossible to produce a child with blood group O (\(ii\)).

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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