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.
Arrange the following events in the life cycle of Plasmodium in the correct sequence, starting when a female Anopheles mosquito bites an infected person:
A. The parasites enter the mosquito’s body and undergo further development.
B. The sporozoites are introduced into the human body when the mosquito bites a human.
C. The parasites multiply within the mosquito to form sporozoites.
D. The sporozoites are stored in the salivary glands of the mosquito.
E. The parasites multiply within the liver cells.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, C, D, B, E
The question starts when a female Anopheles mosquito bites an infected person. The parasites must first get into the mosquito, then turn into sporozoites, be stored in the salivary glands, and only then can a bite pass them on to a human, where they multiply.
A. The parasites enter the mosquito’s body and undergo further development. — First. The passage states that when a female Anopheles mosquito bites an infected person, these parasites enter the mosquito’s body and undergo further development.
C. The parasites multiply within the mosquito to form sporozoites. — Second. Inside the mosquito the parasites multiply to form sporozoites. They can multiply there only after they have entered it.
D. The sporozoites are stored in the salivary glands of the mosquito. — Third. The sporozoites, once formed, are stored in the salivary glands. They cannot be stored before they are formed.
B. The sporozoites are introduced into the human body when the mosquito bites a human. — Fourth. Because they wait in the salivary glands, the sporozoites are passed into the human with the bite.
E. The parasites multiply within the liver cells. — Fifth. The bite initiates the events in the human; the passage states that the parasites initially multiply within the liver cells and then attack the RBCs.