Match Column I with Column II:
| Column I | Column II |
| A. Active immunity | 1. Antibodies received by the foetus from the mother through the placenta |
| B. Physical barriers | 2. Interferons secreted by virus-infected cells |
| C. Passive immunity | 3. Infectious organisms gaining access into the body during natural infection |
| D. Cytokine barriers | 4. Skin and the mucus coating of the epithelium |
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-3, B-4, C-1, D-2
(A) Active immunity — this matches (3) Infectious organisms gaining access into the body during natural infection. In active immunity the body makes its own antibodies after meeting antigens. A natural infection (or a vaccine) brings the antigens in.
(B) Physical barriers — this matches (4) Skin and the mucus coating of the epithelium. They are part of innate immunity. The skin stops microbes from entering, and mucus traps those that enter the tracts.
(C) Passive immunity — this matches (1) Antibodies received by the foetus from the mother through the placenta. In passive immunity ready-made antibodies are received; the body does not make them itself.
(D) Cytokine barriers — this matches (2) Interferons secreted by virus-infected cells. Interferons are proteins that protect the cells not yet infected from the virus.
NCERT Extract:
Innate Immunity – “… Innate immunity consist of four types of barriers. These are — (i) Physical barriers : Skin on our body is the main barrier which prevents entry of the micro-organisms. Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body. … (iv) Cytokine barriers : Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.”
Active and Passive Immunity – “… Active immunity is slow and takes time to give its full effective response. Injecting the microbes deliberately during immunisation or infectious organisms gaining access into body during natural infection induce active immunity. When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity. … The foetus also receives some antibodies from their mother, through the placenta during pregnancy. These are some examples of passive immunity.”