Class 8 Science Chapter 2 MCQ

Anthrax is an infectious disease of humans and animals caused by “Bacillus anthracis”.

Robert coach is known for his role in identification of the causing agent of Anthrax. Edward Jenner is known as father of immunology. He discovered the vaccine for smallpox in 1798. Louis Pasteur discovered fermentation in 1857 by demonstrating the microbes cause souring of milk.

Virus is a micro-organism, which is in an inactive or dead from outside the body of a host. It reproduces or replicates only when it enters a host and reaches its cells.

Carrier or vector are the modes of transmission of a disease. Rest of all are correct. Hence, you answer will be option [C].

Communicable diseases can spread from infected person to others when any person cough or sneeze. When a person suffering from common cold sneezes, fine droplets of moisture carrying thousands of viruses are spread in the air. The virus may enter the body of a healthy person while breathing. It can spread by street food also.

Bacteria can feed and respire. But viruses are the intermediate of living and non-living things. Viruses reproduced when it enters any host body.

Here, all the statements are correct. Hence, your answer will be option [D].

Entamoeba is a protozoan which causes a disease known as amoebic dysentery and plasmodium is a protozoan which causes a disease called malaria in humans.

In 1975 John Bartlett, the discovery of Clostridium difficile and he identified it as the leading cause of hospital-associated infections. Tetanus is caused by a toxin made by spores of bacteria, Clostridium tetani, found in soil, dust and animal feces. When the spores enter a deep flesh wound, they grow into bacteria that can produce a powerful toxin, tetanospasmin. The toxin impairs the nerves that control your muscles (motor neurons).

Here, all the options are correct. Hence, your answer will be option [D].

Here, all the options are correct. Hence, your answer will be option [D].

Antibiotics should be taken only on the advice of “Qualified Doctor”. Qualified doctor means a person who is legally qualified to practice medicine; doctor of medicine. In the other words, a person who engaged in general medical practice, as distinguished from one specializing in surgery.

Measles is caused by infection with the rubeola virus. The virus lives in the mucus of the nose and throat of an infected child or adult. Poliomyelitis is an acute communicable disease of humans. Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV). The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over.

Common cold disease spreads by breathing air containing microbes. Cholera spread by taking infected food or water. AIDS spreads by sharing infected injections, needles with an infected person.

Female Anopheles mosquito which carries the parasite of malaria. Female Aedes mosquito acts as carrier of dengue virus. Malaria is caused by the protozoan parasite Plasmodium.

Typhoid is a bacterial infection that can lead to a high fever, diarrhea, and vomiting. It can be fatal. It is caused by the bacteria Salmonella typhi. Cholera is an infectious disease that causes severe watery diarrhea, which can lead to dehydration and even death if untreated. It is caused by eating food or drinking water contaminated with a bacterium called Vibrio cholerae. Tuberculosis (TB) develops when Mycobacterium tuberculosis bacteria are inhaled into the lungs. The infection usually stays in the lungs.

Here, all the statements are correct about the preventing the occurrence or spreading of communicable diseases. Hence, your answer will be option [D].

Malaria is the disease which is caused by the spread of a “Protozoan” i.e. “Plasmodium”. It is spread in healthy individuals by the bite of a female “Anopheles Mosquito” caring this “Plasmodium” in their mouth (saliva).

We should avoid eating uncovered food items. Rest of all are correct. Hence, your answer will be option [A].

Housefly carries the disease-causing microbes’ outside of its body. Mosquito carries microbes inside its body. Anopheles mosquito carries the plasmodium parasite of malaria.

An inactivated (killed) polio vaccine (IPV) developed by Dr. Jonas Salk and first used in 1955, and. A live attenuated (weakened) oral polio vaccine (OPV) developed by Dr. Albert Sabin and first used in 1961.

Streptomycin is the antibiotics but hemocyanin is a protein found in mollusks that carries oxygen in much the same way as hemoglobin carries oxygen in human blood. Antibiotics are effective to control disease in plants and animals.

Allergic bronchopulmonary aspergillosis (ABPA) is a condition characterized by an exaggerated response of the immune system (a hypersensitivity response) to the fungus Aspergillus fumigatus.

In 1975 John Bartlett, the discovery of Clostridium difficile and he identified it as the leading cause of hospital-associated infections. Tetanus is caused by a toxin made by spores of bacteria, Clostridium tetani, found in soil, dust and animal feces. When the spores enter a deep flesh wound, they grow into bacteria that can produce a powerful toxin, tetanospasmin. The toxin impairs the nerves that control your muscles (motor neurons).

All these statements are correct. Hence, your answer will be option [D].