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Biology · 2026 · 4 marks
CBSE 2026 · Region 4 · Set 1 · Q30
Read the following passage and answer the questions that follow: Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired…
Read the following passage and answer the questions that follow : Immunity in our body is of two types (i) Innate immunity, and
(ii)
Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body - IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.
(a)
Name the two types of specialised cells which carry out the primary and secondary responses.
(b)(i)
Name any two barriers present in our body that provide innate immunity.
OR
(b)
(ii)
The organ transplants (grafts) are often rejected if not taken from suitable compatible persons. Mention the characteristic of our immune system that is responsible for the rejection.
(c)
How is active immunity different from passive immunity ? Write any two differences.
Marking-scheme solution
(a)
B – lymphocytes /B cells , and T – lymphocytes/ T Cells
(b)(i)
Physical barrier , physiological barriers , Cellular barriers , Cytokine barriers
OR
(b)
(ii)
Our immune system has the ability to distinguish between ‘self’ and ‘non-
self’ cells or tissues.
(c)
Active Immunity
Passive Immunity
When antibodies are produced in our body in response to an antigen then it is called active immunity.
When preformed antibodies are
injected into the body for protection then it is called passive immunity.
It is slow and takes time to give its full effective response.
It gives quick response.
It lasts for longer period.
It last for shorter period.
Memory cells are formed.
Memory cells are not formed.
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CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.