Immunity
Read the following passage carefully and answer the given questions.
On daily basis, large number of pathogens are entering our body from the air we breathe in or the food we eat but we are not falling ill daily. It is because of the reason that our body can fight with most of these pathogens entering our body and kill them. Immunity is of two types - acquired or innate immunity. Innate immunity is non specific type of defence which is present from the birth. It is provided by four kinds of barriers - physical, physiological, cellular and cytokine barrier. It is a non specific type of defence. Acquired immunity is acquired when pathogen enters the body. It is pathogen specific and is characterised by memory of the immune system. Acquired immunity is carried out by two special type of lymphocytes called as B-cells and T-cells. B-cells produce antibodies and are responsible for humoral response whereas T-cells produce cell-mediated immune response.
Vaccines recognizes the pathogen on subsequent exposures due to:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Both memory B and T cells
The principle of vaccination is the memory of the immune system. A vaccine contains antigenic proteins of a pathogen or an inactivated or weakened pathogen. It makes the body produce antibodies. It also leaves behind memory cells.
(1) Memory B cells — Incorrect. These are one of the two kinds of memory cells. The other is left out.
(2) Cytokine barriers — Incorrect. This is a barrier of innate immunity, made of interferons secreted by virus-infected cells. It has no memory.
(3) Memory T cells — Incorrect. These are the other kind of memory cell, and the memory B cells are left out.
(4) Both memory B and T cells — Correct. Vaccines make both memory B cells and memory T cells. On a later exposure they recognise the pathogen quickly, and the body makes a massive amount of antibodies.
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:
Vaccination and Immunisation –
