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Question #45839
The Question
A pedigree analysis of a family reveals a high incidence of severe immunodeficiency and MALT (Mucosa-Associated Lymphoid Tissue) lymphomas across successive generations. Molecular studies show that a retrovirus is vertically transmitted from mother to fetus via the placenta. In the offspring, the viral cDNA integrates into somatic cells, causing epigenetic silencing of critical tumor-suppressor genes. Based on NCERT principles of viral replication and human health, which of the following statements regarding this scenario is INCORRECT?
Options
- A.
The transmission pattern mimics maternal inheritance, creating a pedigree trap where an acquired congenital infection appears as an inherited genetic disorder.
- B.
The integration of the viral genome into the host's somatic DNA to form a provirus is catalyzed by the viral enzyme integrase.
- C.
The immunodeficiency and subsequent MALT lymphomas occur because the retrovirus directly infects and destroys B-lymphocytes, crippling humoral immune surveillance.
- D.
Because the viral integration occurs in somatic cells rather than germline cells, the proviral DNA will not be passed to the next generation via the offspring's gametes.
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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
HIV Replication Cycle|MALT Structure|Pedigree Analysis Traps
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot & Functional Confusion Trap: Students often confuse the ultimate clinical effect of a retrovirus (decreased antibody production/humoral failure) with its direct cellular target.
While B-cell function is crippled, the virus directly infects T-helper cells and macrophages, not B-lymphocytes.
Additionally, the question tests the student's ability to synthesize genetics with pathology by distinguishing between a vertically transmitted congenital infection (which mimics maternal inheritance) and a true Mendelian germline mutation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Pedigree Analysis Traps |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |