The toxic substance released upon the rupture of Red Blood Cells (RBCs) in malaria, causing chill and high fever, is:

[Human-Health-and-Disease] [class-xii ]

• Haemoglobin
• Haemozoin
• Dopamine
• Histamine
Correct Option: B  [ Haemozoin ]

Remark: The rupture of RBCs releases a toxic substance, haemozoin, which is responsible for the chill and high fever recurring every three to four days.

How many hosts are required for the malarial parasite to complete its life cycle?

[Human-Health-and-Disease] [class-xii ]

• One host (human only)
• Two hosts (human and mosquito)
• Three hosts (human, mosquito, and cattle)
• Four hosts (human, mosquito, liver, RBCs)
Correct Option: B  [ Two hosts (human and mosquito) ]

Remark: The malarial parasite requires two hosts—human and mosquitoes—to complete its life cycle.

Amoebiasis (amoebic dysentery) is caused by the protozoan parasite:

[Human-Health-and-Disease] [class-xii ]

• Wuchereria bancrofti
• Ascaris lumbricoides
• Entamoeba histolytica
• Plasmodium falciparum
Correct Option: C  [ Entamoeba histolytica ]

Remark: Entamoeba histolytica is a protozoan parasite in the large intestine of human which causes amoebiasis.

Houseflies play a role in the transmission of amoebiasis by acting as:

[Human-Health-and-Disease] [class-xii ]

• Biological vectors
• Intermediate hosts
• Mechanical carriers
• Definitive hosts
Correct Option: C  [ Mechanical carriers ]

Remark: Houseflies act as mechanical carriers and serve to transmit the parasite from faeces of infected person to food.

Ascariasis is caused by the common round worm *Ascaris*. A major symptom of this intestinal parasite is:

[Human-Health-and-Disease] [class-xii ]

• Inflammation of lower limbs
• Blockage of the intestinal passage
• Turning lips bluish
• Chill and high fever
Correct Option: B  [ Blockage of the intestinal passage ]

Remark: Symptoms of ascariasis include internal bleeding, muscular pain, fever, anemia and blockage of the intestinal passage.

Elephantiasis (filariasis) is caused by the filarial worm *Wuchereria* which lives in the body for many years, usually affecting the:

[Human-Health-and-Disease] [class-xii ]

• Small intestine lining
• Liver cells
• Lymphatic vessels of the lower limbs
• Central nervous system
Correct Option: C  [ Lymphatic vessels of the lower limbs ]

Remark: Wuchereria causes a slowly developing chronic inflammation of the organs, usually the lymphatic vessels of the lower limbs.

Which of the following genera of fungi is responsible for causing ringworms?

[Human-Health-and-Disease] [class-xii ]

• Salmonella
• Microsporum, Trichophyton, and Epidermophyton
• Plasmodium
• Ascaris
Correct Option: B  [ Microsporum, Trichophyton, and Epidermophyton ]

Remark: Many fungi belonging to the genera Microsporum, Trichophyton and Epidermophyton are responsible for ringworms.

Ringworms are generally acquired from soil or by using contaminated items such as:

[Human-Health-and-Disease] [class-xii ]

• Drinking water
• Mosquito nets
• Towels, clothes or even the comb of infected individuals
• Intravenous needles
Correct Option: C  [ Towels, clothes or even the comb of infected individuals ]

Remark: Ringworms are acquired from soil or by using towels, clothes or even the comb of infected individuals.

For infectious agents transmitted through food and water (like typhoid and amoebiasis), which public hygiene measure is essential?

[Human-Health-and-Disease] [class-xii ]

• Avoiding close contact with infected people
• Introducing *Gambusia* fish in ponds
• Proper disposal of waste and excreta
• Using wire mesh on windows
Correct Option: C  [ Proper disposal of waste and excreta ]

Remark: Public hygiene includes proper disposal of waste and excreta; cleaning and disinfection of water reservoirs, particularly essential for food- and water-borne diseases.

Which fish is commonly introduced in ponds to feed on mosquito larvae to control vector-borne diseases like malaria and filariasis?

[Human-Health-and-Disease] [class-xii ]

• Catla
• Rohu
• Gambusia
• Pomfret
Correct Option: C  [ Gambusia ]

Remark: Introducing fishes like Gambusia in ponds that feed on mosquito larvae is a vector control measure.