In rare instances, B cells can be found that have two immunoglobulin light chain alleles, both of which are rearranged in frame, and can encode functional light chain proteins. Yet, on the surface of the B cell, only one of the two light chain proteins is detected in the membrane-bound immunoglobulin receptor. The reason these rare cells have two functional light chain rearrangements but only express one of the two light chains as part of the B-cell receptor is:

Correct Answer: B

Rationale: Allelic exclusion ensures one light chain pairs with heavy chain ; pseudogenes , transcription , or RAG don't explain this.

Correct Answer: B

Rationale: Passive immunity involves receiving pre-formed antibodies from another source, not self-production or cell transfer.

Correct Answer: C

Rationale: HIV's high mutation rate creates drug-resistant strains, complicating eradication, not its RNA genome, rare mutation, or size.

Correct Answer: C

Rationale: Zymosan, a fungal cell wall component, is a PAMP, unlike dsRNA (viral), LPS (bacterial), or CpG (bacterial DNA).

Correct Answer: B

Rationale: Antibodies don't form pores (complement does via MAC); they mediate ADCC, neutralization, opsonization, and complement activation.