This set of Class 12 Biology Chapter 8 Multiple Choice Questions & Answers (MCQs) focuses on “Protozoan Diseases in Humans”.
1. Entamoeba histolytica causes _________
c) small Pox
Explanation: Entamoeba histolytica is a pathogen which causes Amoebic Dysentery. Wuchereria bancrofti, Variola virus and Paramyxo virus cause Elephantiasis, Small Pox and Mumps respectively.
2. Entamoeba histolytica is found in _________
c) Small Intestine
d) Large Intestine
Explanation: Entamoeba histolytica causes Amoebic Dysentery or Amoebiasis in the large intestine of humans. Its symptoms include constipation, abdominal pain, cramps and stools with excess mucus and blood clots.
3. The pathogen causing Amoebiasis is transmitted through which of the following?
a) By touch
b) Insect bite
c) Food or water contaminated with cysts
d) Droplet Infection
Explanation: Pathogen which causes Amoebiasis is Entamoeba histolytica. Certain carriers and vectors serve to transmit the parasite from faeces of the infected person to food and food products, thereby contaminating them. So the intake of contaminated food and water are the main source of infection.
4. Which of the following act as mechanical carriers to transmit Entamoeba histolytica?
Explanation: Houseflies act as mechanical carriers to transmit Entamoeba histolytica. Cysts of Entamoeba histolytica present in the stool of infected person are the source of infection.
5. Which of the following species of Plasmodium don’t cause Malaria?
a) Plasmodium piper
b) Plasmodium vivax
c) Plasmodium falciparum
d) Plasmodium malariae
Explanation: There are five species of Plasmodium which cause Malaria. These are Plasmodium vivax, Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale and Plasmodium knowlesi.
6. Out of 5 species of Plasmodium, which one is the most virulent?
a) Plasmodium vivax
b) Plasmodium falciparum
c) Plasmodium malariae
d) Plasmodium knowlesi
Explanation: Plasmodium falciparum is the deadliest species of Plasmodium that cause malaria in humans. It is responsible for causing roughly 50 % of all malaria cases.
7. Where do the sexual stages of Plasmodium develop in its life cycle?
a) Gut of mosquito
b) Brain of human
c) Red Blood Corpuscles of human
d) Liver of human
Explanation: The sexual stages or the gametocytes of Plasmodium develops in Red Blood Corpuscles of the human. The female gametocytes or megagametocytes are round with food-laden cytoplasm and a small excentric nucleus. Male gametocytes or Microgametocytes have a clear cytoplasm and a large central nucleus. Both contain a large amount of haemozoin.
8. In which form Plasmodium enters the human body?
Explanation: Plasmodium enters the human body as sporozoites through the bite of infected female Anopheles. Malarial Parasite requires two hosts to complete its life cycle-Human and Anopheles mosquito which also acts as a vector or a transmitting agent.
9. Shuffner’s dots are related to _________
a) Entamoeba histolytica
c) Red Blood Corpuscles
Explanation: Shuffner’s dots are related to the Red Blood Corpuscles of humans. They are present in the cytoplasm of RBCs. Presence of these granules indicates that RBCs are infected with Plasmodium.
10. When can malarial parasite be obtained in RBCs of a patient?
a) When there is a sudden increase in pulse rate
b) When the temperature rises with rigour
c) When the temperature of a patient suddenly drops
d) When a patient experiences shortness of breath
Explanation: Malarial Parasite can be obtained in the RBCs of the patient when the temperature of the patient rises with rigour. The high temperature of the patient signifies that the RBCs have ruptured and have released Haemozoin toxin in the blood which is responsible for high temperature after every 48 hours with chills and shivering, followed by profuse sweating.
11. Which of the following fish is introduced in a pond to control or eliminate the vector responsible for the transmission of malaria and elephantiasis?
Explanation: For diseases such as Malaria and Elephantiasis that are transmitted through vectors, the most important measure is to control or eliminate the vectors and their breeding places. Therefore, fishes like Gambusia are introduced in ponds which feed on mosquito larvae.
12. Where does the sexual stage of Plasmodium gets completed?
a) In the RBCs of human
b) In the liver of human
c) In the salivary glands of the mosquito
d) In mosquito’s gut
Explanation: When the Anopheles mosquito sucks the blood of an individual infected with Plasmodium pathogen then all the stages of Plasmodium are digested except that of Macrogametocytes and Microgametocytes. Further, fertilisation and development take place inside mosquito’s gut.
13. Malignant tertian/subtertian fever is produced by _________
a) Plasmodium ovale
b) Plasmodium falciparum
c) Plasmodium vivax
d) Plasmodium knowlesi
Explanation: Malignant tertian/subtertian fever is produced by Plasmodium falciparum. This pathogen is the deadliest of all the Plasmodium species. It also causes cerebral malaria and persistent subclinical malaria.
14. Sporozoite stage of Plasmodium is the infective stage to the mosquito.
Explanation: Gametocyte stage of Plasmodium is infective to the mosquito. Sporozoite stage of Plasmodium is infective to Humans.
15. Chloroquine is given to treat which disease?
Explanation: Chloroquine is mainly given to treat malaria. Some other drugs like Quinine (from the bark of Cinchona), camaquine, primaquine and daraprim are also administered to control malaria.
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