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Question #45392
The Question
The developing human fetus expresses paternal antigens, effectively making it a semi-allograft. To prevent maternal immune rejection—a scenario immunologically analogous to a host eliminating an 'intraspecific parasite'—the placenta establishes an endocrine-driven immunological barrier. Which of the following statements regarding maternal-fetal tolerance is INCORRECT?
Options
- A.
High local concentrations of placental progestogens suppress maternal cell-mediated immunity, preventing T-lymphocyte activation against fetal tissue.
- B.
Failure of this local immunosuppression results in maternal immune infiltration and cytokine-mediated destruction of the syncytiotrophoblast.
- C.
Maternal IgG antibodies cross the placenta to bind and mask paternal antigens on the fetal surface, thereby preventing recognition by maternal macrophages.
- D.
Immune-mediated destruction of the placental barrier causes a precipitous drop in human chorionic gonadotropin (hCG) and progesterone, culminating in fetal rejection.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Progesterone|Immunosuppression|Parasitism_Analogy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot & Functional Overlap: Students memorize the NCERT fact that 'IgG crosses the placenta' as a universally protective mechanism for the fetus.
This trap exploits that reflex by misattributing the target of the IgG (paternal antigens instead of pathogens).
It also tests the student's ability to recall that graft rejection is a function of cell-mediated immunity, not humoral immunity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Reproduction - Class 12 |
| Concept | Placental Endocrine Profile |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |