Read the passage and answer the following question:
Some of the human diseases are caused by protozoans too. You might have heard about malaria, a disease man has been fighting since many years. Plasmodium, a tiny protozoan is responsible for this disease. Different species of Plasmodium (P. vivax, P. malaria and P. falciparum) are responsible for different types of malaria. Plasmodium enters the human body as sporozoites (infectious form) through the bite of infected female Anopheles mosquito. The parasites initially multiply within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture. When a female Anopheles mosquito bites an infected person, these parasites enter the mosquito’s body and undergo further development. The parasites multiply within them to form sporozoites that are stored in their salivary glands. When these mosquitoes bite a human, the sporozoites are introduced into his/her body, thereby initiating the events mentioned above. The malarial parasite requires two hosts – human and mosquitoes – to complete its life cycle; the female Anopheles mosquito is the vector (transmitting agent) too.
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): In malaria, the patient suffers from chill and high fever recurring every three to four days.
Reason (R): In malaria, the rupture of red blood cells is associated with release of a toxic substance, haemozoin.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both (A) and (R) are true and (R) is the correct explanation of (A).
In malaria, Plasmodium first multiplies in the liver cells and then enters the red blood cells. The RBCs burst, and what comes out of them makes the patient ill.
Assertion (A): In malaria, the patient suffers from chill and high fever recurring every three to four days. — True. A is about the symptom. Chill and high fever that come back every three to four days are typical of malaria.
Reason (R): In malaria, the rupture of red blood cells is associated with release of a toxic substance, haemozoin. — True. R is about what happens in the blood. When the parasites attack the RBCs, the cells rupture and release haemozoin.
Why R explains A? Haemozoin is the toxic substance that is responsible for the chill and high fever. Each time a fresh round of RBCs ruptures, haemozoin is released again, so the fever keeps coming back. R is the correct explanation of A.
NCERT Extract:
Common Diseases in Humans – “… Plasmodium enters the human body as sporozoites (infectious form) through the bite of infected female Anopheles mosquito. The parasites initially multiply within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture. The rupture of RBCs is associated with release of a toxic substance, haemozoin, which is responsible for the chill and high fever recurring every three to four days.”