Read the given passage carefully and answer the questions.
Salmonella typhi is a pathogenic bacterium which causes typhoid fever in human beings. Sustained high fever (39° to 40°C), weakness, stomach pain, constipation, headache and loss of appetite are some of the common symptoms of this disease. Typhoid fever could be confirmed by Widal test. Plasmodium enters the human body as sporozoites. 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. There is lymphoid tissue also located within the lining of the major tracts (respiratory, digestive and urogenital tracts) called mucosa-associated lymphoid tissue (MALT). In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of regulatory mechanisms. Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancerous cells just continue to divide giving rise to masses of cells called tumors. Tumors are of two types: benign and malignant. Cannabinoids are a group of chemicals, which interact with cannabinoid receptors present principally in the brain. Generally taken by inhalation and oral ingestion, these are known for their effects on cardiovascular system of the body.
The rupture of RBCs is associated with release of a toxic substance, ______ which is responsible for the chill and high fever recurring every three to four days.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Haemozoin
Option (1) Haeme — Incorrect. Haem is the iron-containing part of haemoglobin that binds oxygen. It is a normal part of every red blood cell, not the toxin that causes malarial fever.
Option (2) Haemozoin — Correct. Plasmodium enters the body as sporozoites through the bite of an infected female Anopheles mosquito. It multiplies in the liver cells and then attacks the RBCs. When the RBCs burst, they release the toxin haemozoin, which brings the chill and high fever every three to four days.
Option (3) Haemoglobin — Incorrect. Haemoglobin is the red pigment of RBCs that carries oxygen. It is a useful protein of the blood, not a toxin.
Option (4) Heparin — Incorrect. Heparin is an anticoagulant, a substance that stops blood from clotting. It is secreted by basophils, a kind of white blood cell, and has nothing to do with malaria.
Note 1: 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.
Note 2: A similar question was also asked in CUET (UG) 2025 on 20-05-2025 (Slot 1).