Answer: Innate (non-specific) immunity.
- A Adaptive (specific) immunity
- B Innate (non-specific) immunity
- C Both adaptive and innate
- D Passive immunity
Correct answer: B. Innate (non-specific) immunity
Explanation: NK cells are part of innate (non-specific) immunity. They patrol the body and destroy cells that lack normal self-markers (MHC class I), such as virus-infected cells and cancer cells, without prior sensitization.
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.