Answer: Acquired Immunodeficiency Syndrome caused by HIV, which destroys CD4 + T cells, leading to immune failure.
- A A type of malignant blood cancer that originates from cells within the bone marrow as widely reported
- B Acquired Immunodeficiency Syndrome caused by HIV, which destroys CD4<sup>+</sup> T cells, leading to immune failure
- C A bacterial infection of the lower respiratory tract caused by Mycobacterium tuberculosis in standard practice
- D An inherited genetic disease that affects immune cell development from birth onward under most conditions encountered
Correct answer: B. Acquired Immunodeficiency Syndrome caused by HIV, which destroys CD4<sup>+</sup> T cells, leading to immune failure
Explanation: AIDS (Acquired Immunodeficiency Syndrome) is the advanced stage of HIV infection. HIV destroys CD4<sup>+</sup> T helper cells. When CD4<sup>+</sup> count falls below 200 cells/microlitre, the immune system fails and opportunistic infections develop. No cure, but antiretroviral therapy (ART) controls HIV.
The Plasmodium parasite needs both hosts: the female Anopheles mosquito injects sporozoites while biting (infecting the human liver and RBCs, causing the malaria fever cycle), then picks up gametocytes from an infected person's blood, completing the parasite's sexual stage inside the mosquito.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.