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Question #45603
The Question
An individual possesses the genotype I^A I^B, but their red blood cells fail to agglutinate with either Anti-A or Anti-B sera. Genetic analysis reveals a homozygous recessive mutation at an independent locus (hh). Which of the following statements is INCORRECT regarding this physiological and genetic condition?
Options
- A.
The individual lacks the functional enzyme fucosyltransferase, preventing the synthesis of the H-antigen precursor.
- B.
The I^A and I^B alleles fail to transcribe and translate their respective glycosyltransferases due to the epistatic effect of the hh genotype.
- C.
The individual's blood plasma will contain naturally occurring Anti-A, Anti-B, and Anti-H antibodies.
- D.
This phenomenon represents recessive epistasis, which phenotypically overrides the standard codominance of the ABO locus.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
ABO_Locus|H_Antigen|Fucosyltransferase_Gene
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse 'epistatic masking' with 'gene silencing' or 'transcriptional inhibition'.
The common misconception is assuming that if a phenotype isn't expressed, the gene isn't producing its enzyme.
This trap tests the biochemical reality of recessive epistasis in blood groups—the ABO enzymes are fully synthesized but are functionally useless without the H-antigen precursor.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Multiple Allelism Limitation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |