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CBSE Questions for Class 8 Biology Microorganisms Friend And Foe Quiz 1 - MCQExams.com
CBSE
Class 8 Biology
Microorganisms Friend And Foe
Quiz 1
____________________ is an essential constituent of proteins, nucleic acids, chlorophyll and vitamins.
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Nitrogen
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Hydrogen
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Oxygen
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Calcium
Explanation
Nitrogen is an essential constituent of proteins, nucleic acids, chlorophyll and vitamins.
The correct option is A.
.......... is used to make wine and bread.
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Amoeba
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Yeast
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Tradescantia
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Rhoeo leaf
The disease transmitted by contaminated food and water is:
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Cholera
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Cancer
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Hemorrhage
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Diabetes
Habitat is associated with the ______ one lives in.
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political area
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geographical area
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demographic area
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none of the above
Explanation
Habitat is associated with the geographical area one lives in.
Yeast is used in the production of .............
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sugar
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alcohol
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Hydrochloric acid
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oxygen
Which of the following is correctly matched regarding an institute and its location?
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National Institute of Virology - Pune
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National Institute of Communicable Diseases - Lucknow
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Central Drug Research Institute - Kasauli
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National Institute of Nutrition - Mumbai
Salt is used to preserve food by removing .......... from it.
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Moisture
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Microbes
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Air
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All of the above
Explanation
There are different methods for the preservation of the food. Salting is one of the oldest methods which is used for the preserving food for a long time. The food is soaked in salt or brine water. The addition of salt removes the moisture by the process of exosmosis. The presence of salt and no moisture prevents bacterial contamination. So, the food does not get degraded for a longer period of time.
Thus, the correct answer is option A.
Which is not a biological agent of disease?
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Fungi
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Mycoplasma
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Pollen
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Bacteria
Explanation
A pathogen is an infectious microorganism or an agent such as a virus, bacteria, protozoan, fungus etc. which are able to cause disease.
Fungi is a eukaryote which is the common cause of disease in crops and other plants. It can also cause disease in humans and animals.
Mycoplasma is a genus of bacteria which causes diseases in humans (such as tuberculosis) and plants.
Bacteria also cause infectious diseases in human beings and animals.
Pollen is a fine to coarse, powdery substance comprising pollen grains which are male microgametophytes of seed plants.
So, the correct answer is option C- 'Pollen'.
The organisms which cannot be seen with the naked eyes are called
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Plants
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Microorganisms
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Animals
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All of the above
Explanation
The microorganisms are the microscopic bodies which cannot be seen directly with the naked eye. These organisms are of the size in microns. The study which deals with the microbes is known as microbiology. There are the different types of microbes like bacteria, viruses, fungi, etc.
Thus, the correct answer is option B.
Which of following microorganism helps in fermentation?
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Yeast
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Mould
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Mushroom
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Rhizopus
Explanation
The yeast is a type of fungal species which have unicellular cells. These cells are known to perform anaerobic respiration or fermentation of the sugars that produce alcohol and carbon dioxide in the absence of oxygen.
Thus, the correct answer is option A.
Microbiology is
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Study of bacteria
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Study of virus
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Study of fungi
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Study of microbes
Explanation
The microorganisms are the microscopic bodies which cannot be observed directly with the naked eye. The study which deals with all the properties of the microbes is known as microbiology. This field includes the type of microbes, their structures, their characteristics, their interactions, etc. There are different fields which deal specifically with one type of microbe like virology, bacteriology, mycology, etc.
Thus, the correct answer is option D.
Which antibiotic is extracted from fungi?
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Streptomycin
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Penicillin
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Chloromycetin
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Framycetin
Explanation
Penicillin is antibiotic or the drug which is produced by the fungal species
Penicillium notatum
. The antibiotic is very useful in the treatment of the infections caused by
Streptococcus
and
Staphylococcus
species. This antibiotic was discovered by Alexander Flemming.
Thus, the correct answer is option B.
Tuberculosis is caused by a
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Bacterium
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Virus
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Protozoan
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Malnutrition
Explanation
The
Mycobacterium tuberculosis
bacterium causes TB. It is an obligate bacteria. It spreads through the air from person to person. Lungs are the most common organ which is affected by tuberculosis so they are specifically known as pulmonary tuberculosis.
So, the correct answer is option B.
Which one of the following is a water-borne disease?
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Small pox
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Malaria
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Tuberculosis
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Cholera
Explanation
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
. The disease is most common in places with poor sanitation, crowding, war, and famine.
So, the correct answer is option B.
Study the following lists & choose The correct match is
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A-IV,B-I,C-II,D-III
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A-II,B-III,C-IV,D-V
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A-V,B-IV,C-III,D-II
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A-III,B-II,C-I,D-IV
Malaria is transmitted by:
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Male
Culex
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Female
Culex
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Male
Anopheles
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Female
Anopheles
Explanation
Malaria is caused by infection of Plasmodium species with human blood. Plasmodium resides and multiplies in the female Anopheles mosquito.
Hence, option D is correct.
Cholera is caused by a ________.
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Virus
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Bacteria
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Fungi
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Protozoan
Explanation
Cholera is an infectious disease, that causes severe watery diarrhoea, leading to dehydration. If untreated, it may lead to the death of the person.
Cholera is caused by consuming contaminated food or water.
The bacteria responsible for causing the disease is a bacterium, called
Vibrio cholerae
.
The disease is most common in places with poor sanitation, crowding, war, and famine.
So, the correct answer is option B.
Inoculation of a suspension of killed or attenuated pathogenic micro-organisms to stimulate the formation of antibodies is known as
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Vaccination
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Antibiotic treatment
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Serum therapy
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Transplantation
On which day, we celebrate world 'Malaria Day'?
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5th June
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15th August
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25th April
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20th September
Vaccines are prepared from:
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Vitamins
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Blood
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Attenuated bacteria or inactivated viruses
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Plasma
Explanation
A vaccine
contains weakened or inactivated microorganisms such as bacteria or viruses. These inactive organisms trigger an immune response by
producing
antibodies within the body. These antibodies protect the body from further infection.
Thus, the correct answer is option (C),
Pasteurization is heating at
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$$120^{0}$$C for 60 minutes
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60-$$70^{0}$$C for 30 minutes
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$$70^{0}$$'C for 60 minutes
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$$80^{0}$$C for 30 minutes
Explanation
In the classic pasteurization treatment of milk, the milk
was exposed to a temperature of about $$63^{0}$$C for 30
minutes. Most milk pasteurization today uses higher
temperatures, at least $$72^{0}$$C, but for only 15 seconds.
Heating milk at $$70^{0}$$ followed by sudden cooling is known as ______________.
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Sterilization
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Preservation
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Pasteurization
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Fermentation
Explanation
The milk is heated to about 70 degree celsius 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. It is called pasteurization.
Pneumonia is an example of
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Communicable disease
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Non-communicable disease
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Genetic disease
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Both A and C
Explanation
Pneumonia is caused by a bacterial pathogen.
They can be transmitted from a contaminated person to a healthy person by sneezing, coughing, contaminated objects, etc. Thus, it is considered a communicable disease.
So, the correct answer is option A.
Which of the following is an air-borne disease?
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Tuberculosis
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Cholera
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Jaundice
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Brain fever
Explanation
A disease that is transmitted through the medium of air is said to be airborne. Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis. It is transmitted by the small particles or droplet nuclei that harbor these pathogens. When a person suffering from this disease sneezes, coughs or talks the pathogen in the droplet nuclei are carried by air. This may infect another person who inhales these droplet nuclei.
Thus the correct answer is option A.
Which one of the following is not a viral disease?
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Dengue
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AIDS
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Typhoid
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Influenza
Explanation
Dengue fever is caused by any one of four dengue viruses spread by mosquitoes that thrive in and near human lodgings.
AIDS is caused by the Human immunodeficiency virus (HIV).
Influenza is caused by the influenza virus.
Typhoid is caused by
Salmonella typhi
, which is a bacteria.
Which of the following microorganisms converts milk into curd?
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Spirogyra
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Aspergillus
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Penicillium
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Lactobacillus
Explanation
Lactobacillus
is a bacterium that converts milk into curd. It acts on the lactose part of the milk and turns it into lactic acid. The increased acidity leads to the coagulation of the casein protein of the milk and turns it into curd.
So, the correct answer is option D.
W
hich of the following are commonly used as food preservatives?
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Boric acid and zinc phosphide
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Bleaching powder and chlorine compounds
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2, 4-D and zinc phosphide
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Sodium benzoate and sodium metabisulphite.
Explanation
Food preservatives are chemicals that are used to inhibit microbial growth in food.
These chemicals are food additives and increase the shelf life of food.
Sodium benzoate and sodium metabisulphite are the common food preservatives used in jams, jellies, etc.
Thus the correct answer is option D.
Disease-causing microorganisms are killed or inhibited by medicines called
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Pain killers
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Antibodies
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Antibiotics
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Vaccines
Explanation
An antibiotic is a chemical substance that inhibits the growth of bacteria. They hinder the reproductive cycle of the bacteria inside the body of the host.
So, the correct answer is option C.
Which among the following control measures would not help preventing the spread of malaria?
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Covering windows with netting
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Drinking boiled water
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Keeping surroundings dry and clean
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Spraying insecticides on stagnant water
Explanation
Malaria is spread by the bite of mosquito as it the vectors for this disease. Mosquito breed in stagnant waters. Hence insecticides should be sprayed on stagnant water.
The surrounding should be kept clean and dry that minimizes the breeding grounds of mosquitoes such small stagnant water pools, gutters, etc.
The windows should be covered and netted to prevent mosquito entry into the house. They above are control measures to prevent the spread of malaria.
Thus the correct answer is option B.
Which of the following are called pathogens?
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Viruses, Bacteria, Fungi and Protozoans
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Measles, Mumps and Chicken pox
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Cholesterol, Saturated fat and Helminthes
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Cholera, Typhoid, Tuberculosis and Measles
Explanation
Pathogens are life forms that transmit diseases which result in various illness in humans, animals, plants and other living creatures. Viruses, Bacteria, Fungi and Protozoans are pathogens responsible for various diseases.
Some pathogens and the disease caused:
Bacteria - For example,
cholera.
Virus - For example,
Hepatitis.
Fungus - For example, Candidiasis.
Protozoa - For example, Malaria.
Thus the correct answer is option A.
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