Read the passage carefully and answer the questions given below.
Our immune system plays the major role in preventing diseases when we are exposed to disease-causing agents. Immunity is of two types: (i) Innate immunity and (ii) Acquired immunity. The human immune system consists of lymphoid organs, tissues, cells and soluble molecules like antibodies. The immune system also plays an important role in allergic reactions, auto-immune diseases and organ transplantation. The primary lymphoid organs are bone marrow and thymus. The secondary lymphoid organs are spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix. There is lymphoid tissue also located within the lining of the major tracts (respiratory, digestive and urogenital tracts) called mucosa associated lymphoid tissue (MALT). It is important to note that HIV/AIDS is not spread by mere touch or physical contact it spreads only through body fluids. AIDS has no cure, prevention is the best option. Adolescence is accompanied by several biological and behavioural changes and surveys and statistics show that use of drugs and alcohol has been on the rise especially among the youth. Factors associated with drug and alcohol abuse among adolescents are a child's natural curiosity, stress, the perception among youth that it is 'cool' or progressive to smoke, media exposure and an unstable or unsupportive family structures and peer pressure. It is best to identify the situations that may push an adolescent towards use of drugs or alcohol, and to take remedial measures well in time.
Active immunization is most suitable method for:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Natural infection
In active immunity the body makes its own antibodies after meeting an antigen. It is slow but long-lasting. In passive immunity ready-made antibodies are given, so protection is quick but short.
Option (1) Exposure to snake venom — Incorrect. Snake venom acts fast, so the patient is given ready-made antibodies (antitoxin). That is passive immunisation.
Option (2) Natural infection — Correct. When a microbe gets into the body in a natural infection, the body makes its own antibodies and memory cells, which is active immunity.
Option (3) Deadly microbe infection — Incorrect. A deadly infection needs a quick immune response, so preformed antibodies are injected (passive immunisation), as for tetanus.
Option (4) Protection of fetus in the womb — Incorrect. The foetus gets antibodies from its mother through the placenta. They are not made by the foetus, so this is passive immunity.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Active and Passive Immunity – “When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active 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.”