Test: Microorganisms Friend & Foe- 1 - Class 8

• Tuberculosis is an air-borne disease caused by the bacterial species Mycobacterium tuberculosis.
• Polio, dengue and chicken pox are viral diseases caused by Picornavirus, Flavivirus and chicken pox virus respectively.

Pasteurization is a process in which milk is heated to about 70oC for 15 to 30 seconds and then suddenly chilled and stored. By doing so, it prevents the growth of microbes. This process was discovered by Louis Pasteur and hence is called pasteurization.

• Living organisms which are invisible to the naked eye are called microorganisms. Microorganisms are too small to be seen with our naked eyes. They can be seen only through a device known as a microscope.

A vaccine is a biological preparation containing weakened or dead microbes. It is introduced into a healthy person’s body so that it can produce antibodies against the disease-causing microbes. Vaccines can be injected or administered orally.

Lactobacillus is the microorganism present in curd. This bacterium converts milk into curd at 30 to 40oC.

While baking cakes, yeast reproduces rapidly and produces carbon dioxide gas. This gas is responsible for the spongy texture of cake.

Yeast is used for the production of alcohol and wine by the process of fermentation.

Antibiotics are the medicines that kill or stop the growth of disease-causing microorganisms. Streptomycin, tetracycline and erythromycin are some of the commonly known antibiotics which are made from fungi and bacteria. Antibiotics are mostly effective against bacterial diseases. Among the diseases given, only typhoid is caused by bacteria, i.e., Salmonella typhi, whereas all the other diseases are caused by protozoa or viruses.