Observe the diagram and answer the following question :
Diagrammatic representation of Lymphatic system.
Identify the primary lymphoid organs :
(A) Lymph nodes
(B) Bone marrow
(C) Thymus
(D) Tonsils
Choose the correct answer from the options given below :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (B) and (C) Only
(A) Lymph nodes — Incorrect. Lymph nodes are secondary lymphoid organs, where lymphocytes meet antigens.
(B) Bone marrow — Correct. All blood cells, lymphocytes included, are made here.
(C) Thymus — Correct. T-lymphocytes mature here.
(D) Tonsils — Incorrect. Tonsils are secondary lymphoid organs.
NCERT Extract:
Immune System in the Body – “… Lymphoid organs: These are the organs where origin and/or maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes. After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix.”
