Before You Begin
Question #46463
The Question
In higher vertebrates, the generation of high-affinity antibodies during an infection mimics micro-evolution: B-cells undergo random genetic changes (somatic hypermutation) followed by directional selection for the best-fitting antigen receptors. If these highly specific 'selected' antibodies later cause an autoimmune condition such as Rheumatic fever, which of the following represents the most accurate mechanistic explanation?
Options
- A.
The pathogen possessed antigens structurally homologous to host tissue proteins, leading to cross-reactivity by the selected high-affinity clones.
- B.
Somatic hypermutation occurred in the primary lymphoid organs, bypassing the negative selection of self-reactive B-cells.
- C.
Directional selection in the lymph nodes favored the production of auto-reactive T-lymphocytes instead of B-lymphocytes.
- D.
The pathogen suppressed the host's innate immunity, forcing the adaptive immune system to target self-cells for antigen presentation.
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
Clonal Selection|Variable Region|Hypermutation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The question tests the synthesis of evolutionary biology (directional selection) with advanced immunology (affinity maturation and molecular mimicry).
The primary trap (Option B) relies on Location Specificity-students often forget that while B-cell maturation begins in the bone marrow (primary), somatic hypermutation and clonal selection occur in the germinal centers of secondary lymphoid organs after antigen exposure.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Natural Selection Directionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |