Question

Read the sources given and answer any four from the questions given below:

The human immune system consists of lymphoid organs, tissues, cells and antibodies. Lymphoid organs are those organs where the maturation and proliferation of lymphocytes take place. There are two types of lymphoid organs: primary and secondary. Primary lymphoid organs are the sites of origin and where the proliferation of lymphocytes occurs. These are bone marrow and thymus. In bone marrow all blood cells including lymphocytes are produced. Thymus is a lobed organ located near the heart and beneath the sternum. In bone marrow, the immature B lymphocytes while in thymus, the immature T lymphocytes mature and differentiate. After maturation, these B and T lymphocytes migrate to secondary lymphoid organs. Secondary lymphoid organs are the sites where lymphocytes interact with specific antigens and differentiate in response to that. These organs include lymph nodes, spleen and Peyer's patches in small intestine where lymphocytes reach via the circulatory system

1. B and T lymphocytes originate in the following organs
   1. thymus
   2. bone marrow
   3. primary lymphoid organs
   4. lymph nodes
2. The interaction of lymphocytes with antigens occurs in the
   1. bone marrow
   2. thymus
   3. primary lymphoid organs
   4. secondary lymphoid organs
3. Where is thymus gland present?
   1. lymph nodes
   2. near the heart beneath sternum
   3. above thyroid gland
   4. intestine
4. Function of secondary lymphoid organs is
   1. differentiate in response to specific antigen
   2. B lymphocytes mature
   3. Tlymphocytes mature
   4. both (b) and (c)
5. Following organ is not an example of secondary lymphoid tissue.
   1. spleen
   2. Peyer's patch
   3. lymph nodes
   4. thyroid

Answer 1

1. primary lymphoid organs
2. secondary lymphoid organs
3. near the heart beneath sternum
4. differentiate in response to specific antigen
5. thyroid