Match List-I with List-II
| List-I | List-II |
|---|---|
| Lymphoid organs | Characteristics |
| (A) Bone marrow | (I) Primary lymphoid organ |
| (B) Lymph nodes | (II) Produce lymphocytes |
| (C) Spleen | (III) Trap the micro-organisms or other antigens |
| (D) Thymus | (IV) Large reservoir of erythrocytes |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) - (II), (B) - (III), (C) - (IV), (D) - (I)
(A) Bone marrow — this matches (II) Produce lymphocytes. All blood cells, including the lymphocytes, are made in the bone marrow.
(B) Lymph nodes — this matches (III) Trap the micro-organisms or other antigens. Lymph nodes lie along the lymph vessels. They hold back antigens in the lymph, and these antigens activate the lymphocytes there.
(C) Spleen — this matches (IV) Large reservoir of erythrocytes. The spleen is a bean-shaped organ that filters the blood and stores a large reserve of red blood cells.
(D) Thymus — this matches (I) Primary lymphoid organ. In the thymus the lymphocytes (T-cells) mature and become able to recognise antigens. Such an organ is a primary lymphoid organ.
Note: Bone marrow is also a primary lymphoid organ, and the thymus also makes mature lymphocytes, so (I) and (II) can each fit both (A) and (D). The spleen also traps blood-borne microbes, so (III) can fit (C) as well as (B). Only Option (3) is consistent, because it is the only one that gives (B) Lymph nodes (III) and (C) Spleen (IV).
NCERT Extract:
Lymphoid Organs – “… 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.”
Lymphoid Organs – “… The bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced. The thymus is a lobed organ located near the heart and beneath the breastbone. The thymus is quite large at the time of birth but keeps reducing in size with age and by the time puberty is attained it reduces to a very small size. Both bone-marrow and thymus provide micro-environments for the development and maturation of T-lymphocytes. The spleen is a large bean-shaped organ. It mainly contains lymphocytes and phagocytes. It acts as a filter of the blood by trapping blood-borne micro-organisms. Spleen also has a large reservoir of erythrocytes. The lymph nodes are small solid structures located at different points along the lymphatic system. Lymph nodes serve to trap the micro-organisms or other antigens, which happen to get into the lymph and tissue fluid.”