Question

Which of the following are secondary lymphoid organs?
(a) Bone marrow
(b) Tonsils
(c) Spleen
(d) Thymus
Choose the correct answer from the options given below :

• (a) and (d) only
• (a) and (b) only
• (b) and (c) only
• (b) and (d) only

Hint:

Bone marrow is the principal site of lymphocyte production, where both B and T cell precursors are generated. The spleen acts as a main biological filter, trapping blood-borne microorganisms and worn-out erythrocytes.

Answer 1

The Correct Option is C

Concept:

• Lymphoid organs are classified into two main types depending on their role in the immune system: itemize

• Primary Lymphoid Organs: Tissues where immature lymphocytes differentiate and mature into antigen-sensitive cells. These are

Bone marrow and the

Thymus.

• Secondary Lymphoid Organs: Tissues where mature lymphocytes travel to interact with specific foreign antigens and multiply. These include the

Spleen, lymph nodes,

tonsils, Peyer's patches, and appendix.
itemize

Step 1: Classify each of the listed lymphoid organs
(a) Bone marrow \(\rightarrow\) Primary lymphoid organ
(b) Tonsils \(\rightarrow\) Secondary lymphoid organ
(c) Spleen \(\rightarrow\) Secondary lymphoid organ
(d) Thymus \(\rightarrow\) Primary lymphoid organ

Step 2: Identify the secondary organs and choose the option
The secondary lymphoid organs are (b) and (c), which is represented by option (3).