Class 8 Science Chapter 2 MCQ

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

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.

Rust of wheat is caused by fungi which is a disease in plants. Therefore, option [B] is non-benefits of microorganisms.

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.

Influenza is an infectious disease caused by the influenza virus. It is also known as flu symptoms include high fever, running nose, sore throat, headache, coughing and muscles pain etc. Typhoid, dysentery and cholera are bacterial infections.

Foot and mouth disease is caused in cattle by a virus. Wheat of rust is a fungal disease in plants. Yellow vein mosaic of bhindi (okra) is a viral disease in plants.

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

Antibiotics are substances that may inhibit or kill the growth of different microbes. Microorganisms causing infection in host bodies are killed by consumption of these antibiotics.

Spirogyra is multi-celled algae. Chlamydomonas and diatoms are single-celled algae. Blue-green algae can fix nitrogen gas of atmosphere.

All fungi are made up of fine threads, except “yeast”.

Lichens is an association between fungal and an algal species. It is a mutually benefiting association where algae provide food to the fungus and in return gets shelter from it.

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.

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.

Healthcare providers (doctors, nurses, and anyone providing injections) should never reuse a needle or syringe either from one patient to another or to withdraw medicine from a vial. Both needle and syringe must be discarded once they have been used.

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.

Bacillus anthracis is an aerobic spore-forming bacterium that causes disease in humans and animals. The bacteria is found in two forms: cutaneous anthrax and inhalation anthrax. Cutaneous anthrax is an infection of the skin caused by direct contact with the bacterium.

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

Malaria is not caused by a virus or bacteria. Malaria is caused by a parasite known as Plasmodium, which is normally spread through infected mosquitoes. A mosquito takes a blood meal from an infected human, taking in Plasmodia which are in the blood. Ronald Ross is famous for his work concerning malaria and was awarded the Nobel Prize for Physiology or Medicine in 1902. He discovered that the salivary gland in the mosquito was the storage site of malarial parasites and using infected birds, he demonstrated the full life cycle of the malarial parasitic organism

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.

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.

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].