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Biology · 2025 · 2 marks
CBSE 2025 · Region 2 · Set 1 · Q19
Student to attempt either option (A) or (B). (A) Describe any two situations where a medical doctor would recommend injection of a pre-formed…
Student to attempt either option (A) or (B).
(A)
Describe any two situations where a medical doctor would recommend injection of a pre-formed antibodies (antitoxins) into the body of a patient.
OR
(B)
The symptoms of malaria do not appear immediately after the entry of sporozoites into the human body when bitten by female Anopheles mosquito. Explain why it happens.
Marking-scheme solution
$\displaystyle \star$ In case of snakebite, quick response is required as natural production of antibodies will take more time therefore preformed antibodies against the snake venom are injected.
$\displaystyle \star$ In tetanus, preformed antibodies are directly injected because quick immune response is required against deadly microbes.
The symptoms do not appear immediately as parasite initially multiply within the liver cells, and then attack RBCs, resulting in their rupture and, release toxic substance haemozoin.
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CBSE Class 12 Biology past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.