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🔬 Biology  ·  Human Health and Disease  ·  NEET

Which of the following is a primary lymphoid organ?

Answer: Thymus.

  • A Spleen
  • B Lymph nodes
  • C Thymus
  • D Tonsils

Correct answer: C. Thymus

Explanation: Bone marrow and the thymus are primary (central) lymphoid organs where immature lymphocytes mature. Spleen, lymph nodes, tonsils and MALT are secondary lymphoid organs.

Malaria Transmission CycleHumanhostAnophelesmosquito (vector)bites human, injects sporozoitesbites infected human, takes gametocytesSporozoites infect liver,then RBCs (causes fever)Parasite completes sexualstage inside the mosquito

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.

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