Question

Study the following statements regarding immune system and identify the correct statements.
A) Humoral immunity helps in apoptosis.
B) Destruction of microbes by natural killer cells is called first line of defence.
C) The mature lymphocytes are transformed into functional lymphocytes in appendix.
D) The attack of HIV on certain tissues is referred as tissue tropism.

• A. C & D
• B. A & C
• C. B & D
• D. A & B

Hint:

Remember: Primary lymphoid organs (bone marrow, thymus) are sites of lymphocyte production and maturation.
Secondary lymphoid organs (spleen, lymph nodes, tonsils, Peyer's patches, appendix) are sites where mature lymphocytes become functional effector cells.

Answer 1

The Correct Option is A

Step 1: Check statement A.
Humoral immunity works through antibodies neutralising pathogens, apoptosis of infected cells is actually the job of cell mediated immunity, so A is wrong.
Step 2: Check statement B.
Natural killer cells are indeed innate defenders, but physical barriers like skin and mucus form the true first line of defence, NK cells act a step later, so B is wrong.
Step 3: Check statements C and D.
Lymphocytes produced in bone marrow and thymus do mature functionally in secondary lymphoid tissue such as the appendix, and HIV's preference for attacking specific cell types like helper T cells is indeed called tissue tropism, both hold up.
Final answer: Option 1, statements C and D are correct.