Acquired immunity is characterised by memory. Identify the sequence in which it happens :
(A) Subsequent encounter of the body with same pathogen
(B) Primary response is produced when the body encounter pathogens for the first time
(C) T-lymphocytes help B-lymphocytes to produce an army of proteins
(D) Body exhibits highly intensified anamnestic response
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (B), (C), (A), (D)
The body first meets a pathogen and gives a primary response (B), in which T-lymphocytes help B-lymphocytes produce antibodies (C). On a later encounter with the same pathogen (A), the body gives a highly intensified anamnestic (secondary) response (D).
NCERT Extract:
Acquired Immunity – “… Acquired immunity, on the other hand is pathogen specific. It is characterised by memory. This means when our body encounters a pathogen for the first time it produces a response called primary response which is of low intensity. Subsequent encounter with the same pathogen elicits a highly intensified secondary or anamnestic response. This is ascribed to the fact that our body appears to have memory of the first encounter.”