Test: Microorganisms : Friend Or Foe (Hard)


20 Questions MCQ Test Science Class 8 | Test: Microorganisms : Friend Or Foe (Hard)


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This mock test of Test: Microorganisms : Friend Or Foe (Hard) for Class 8 helps you for every Class 8 entrance exam. This contains 20 Multiple Choice Questions for Class 8 Test: Microorganisms : Friend Or Foe (Hard) (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Microorganisms : Friend Or Foe (Hard) quiz give you a good mix of easy questions and tough questions. Class 8 students definitely take this Test: Microorganisms : Friend Or Foe (Hard) exercise for a better result in the exam. You can find other Test: Microorganisms : Friend Or Foe (Hard) extra questions, long questions & short questions for Class 8 on EduRev as well by searching above.
QUESTION: 1

Name the unicellular or multicellular microorganism which is found in water.

Solution: Because most of these micro-organisms are green in color, while few may be yellowish-brown. Algae are also diverse and may either be Unicellular and Multicellular. Some of the most common forms of algae that may be found in pond water include sphingomonas, euglena as well as Chlamydomonas.

QUESTION: 2

Lactobacillus is an example of ___________ .

Solution: Lactobacillus is a type of bacteria. There are many species of lactobacillus. These are "friendly" bacteria that normally live in our digestive, urinary, and genital systems without causing disease.

QUESTION: 3

Penicillium and Aspergillus are examples of __________ .

Solution: Fungi are multicellular, heterotrophic microorganisms found in colonies. Hence, Penicillium and Aspergillus are examples of fungi.

QUESTION: 4

Which of the following diseases is caused by bacteria?

Solution:
  • Tuberculosis is an air-borne disease caused by the bacterial species Mycobacterium tuberculosis.

  • Polio, dengue, and chickenpox are viral diseases caused by Picornavirus, Flavivirus, and chickenpox virus respectively.

QUESTION: 5

Some plants have nitrogen-fixing bacteria in their root nodules. What are these bacteria called?

Solution: Leguminous plants like peas have nitrogen-fixing bacteria called Rhizobium in their root nodules. Rhizobium helps in converting atmospheric nitrogen into ammonia that can be utilized by the pea plant for its nutrition. Other bacteria like Nitrosomonas and Azotobacter are free-living soil bacteria that also help in nitrogen fixation.

QUESTION: 6

In order to take precautionary steps to control dengue, we must take measures to stop the breeding of

Solution: Dengue is caused by a virus and is spread by a species of mosquito called Aedes. The spread of this disease can be prevented by using mosquito nets, repellents and by control of the breeding of mosquitoes by not allowing water stagnation in our surroundings.

QUESTION: 7

Partial sterilization of a product such as milk at a high temperature is known as:

Solution: 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.

QUESTION: 8

Living organisms which are invisible to the naked eye are called _________.

Solution: Living organisms that 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.

QUESTION: 9

Which of the following is a communicable disease?

Solution: Chickenpox is a communicable disease. Communicable diseases are caused by pathogens and can be spread from one person to another through water, air, soil, etc.

QUESTION: 10

Vaccines are made up of

Solution: 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.

QUESTION: 11

The bacterium present in curd is:

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

QUESTION: 12

While baking cakes, yeast reproduces rapidly and produces ___ gas.

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

QUESTION: 13

Which of the following diseases can be cured using antibiotics?

Solution: Antibiotics are 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.

QUESTION: 14

Which organisms are microscopic and dependent on host organisms for reproduction?

Solution: Viruses are non-cellular microorganisms composed of protein, nucleic acids, and lipids. Viruses are considered both living and non-living organisms. They are active inside host cells and reproduce inside them by infecting living cells. Outside a host, it is considered non-living as it does not have cellular machinery of its own.

QUESTION: 15

An infectious disease is ___________ .

Solution: Infectious diseases are caused by any pathogenic microorganisms such as bacteria, viruses, parasites, or fungi. The diseases can be spread, directly or indirectly, from one person to another.

QUESTION: 16

Which among the following statements is not associated with food preservation?

Solution:
  • Food preservation is the prevention of the growth of bacteria, fungi, and other microorganisms in food items.

  • There are different methods of preserving food. For example, packaging, smoking, drying, pickling, etc.

  • Food preservation also prevents spoilage of food and increase their shelf life.

QUESTION: 17

Which one of the following is not produced by the process of fermentation?

Solution: The breakdown of carbon-containing substances like carbohydrates in the absence of oxygen by microorganisms like yeast and bacteria is termed as fermentation. Fermentation is involved in making bread, vinegar, yoghurt, wine, cider, cocoa, cheese, etc.

QUESTION: 18

A plant disease called citrus canker is caused by a _________.

Solution: Citrus canker is a plant disease caused by bacteria. Its mode of transmission is through the air.

QUESTION: 19

Which among the following pathogens causes cholera?

Solution: Cholera is caused by bacteria. It spreads through contaminated food and water. It can be prevented by consuming properly cooked food and drinking boiled water.

QUESTION: 20

Alcohol is produced with the help of

Solution: The type of alcohol in the alcoholic drinks we drink is a chemical called ethanol. To make alcohol, you need to put grains, fruits or vegetables through a process called fermentation (when yeast or bacteria react with the sugars in food - the by-products are ethanol and carbon dioxide).