Question

Match column I with column II and select the correct option.

• A. A - 3, B - 1, C - 4 and D - 2
• B. A - 2, B - 3, C - 4 and D - 1
• C. A - 3, B - 4, C - 1 and D - 2
  
• D. A - 1, B - 1, C - 4 and D - 3

Answer 1

The correct option is A A - 3, B - 1, C - 4 and D - 2

The immune system is a network of immune cells and chemicals that works in coordination to protect our body from the foreign invaders. It includes the first, second and third line of defences.

First line of defence include mainly the physical and physiological barriers like skin and secretions of the skin and mucous membranes, lysozymes in tears and saliva. It prevents the invasion of microorganisms. Lysozymes destroy the peptidoglycan in the cell wall and kill the bacterial cells.

Second line of defence also give non specific (not against a particular pathogen) immunity. It consists of the immune cells like macrophages and neutrophils which attack the pathogens, phagocytose (cell eating) and destroy them. It also includes inflammatory reactions like swelling, pain and redness.

Third line of defence is specific against the pathogens. A person acquires this defence mechanism by getting exposed to antigens in his lifetime. So it is also called adaptive/acquired immunity.