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CBSE Questions for Class 8 Biology Microorganisms Friend And Foe Quiz 4 - MCQExams.com
CBSE
Class 8 Biology
Microorganisms Friend And Foe
Quiz 4
Mark the correct statement.
(A) Common salt has been used to preserve meat and fish for ages.
(B) Meat and fish are covered with dry salt to check the growth of bacteria.
(C) Salting is also used to preserve amla, raw mangoes, tamarind, etc.
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(A) and (B) only
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(B) and (C) only
0%
(A) and (C) only
0%
All of the above
Explanation
Common salt has been used to preserve meat and fish for ages. Meat and fish are covered with dry salt to check the growth of bacteria. Salting is also used to preserve amla, raw mangoes, tamarind, etc.
Common salt reduce the water content, thus inhibiting the bacterial growth on the food items.
So, the correct answer is option D.
Suspensions of killed or weakened microbes or derivatives of microorganisms are called ________
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Drugs
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Probiotics
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Vaccines
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Antibiotics
Explanation
Vaccines are suspensions of killed or weakened microbes or products or derivatives of micro organisms. A vaccine produces immunity to a disease by stimulating the production of antibodies.
Salt is used in raw mangoes, amla, tamarind for
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Enhancing the taste
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Enhancing the colour of pickle
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Preservation
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None of the above
Explanation
Common salt has been used to preserve meat and fish for ages. Meat and fish are covered with dry salt to check the growth of bacteria. Salting is also used to preserve amla, raw mangoes, tamarind, etc.
Common salt reduce the water content.
So, the correct answer is '
As a preservative'
Vaccines are important for
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Children
0%
Adults
0%
Both A and B
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None of the above
Explanation
Vaccines are the suspension of weakened or killed microorganism which generates the immune response.
It provides active acquired immunity to a particular disease. It is
important for both, adults and children, as they can protect us from the
many diseases.
So, the correct answer is option C.
A boy was invited by his friend to a party and he ate a variety of foodstuff. On reaching home he started vomiting. He had to be taken to a hospital. The doctor said that this condition could be due to ________
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Empty stomach
0%
Food poisoning
0%
Due to weak stomach movement
0%
All of the above
Explanation
Since he ate variety of foodstuffs,the condition could be due to food poisoning.
Food poisoning could be due to the consumption of food spoilt by some microorganisms. Microorganisms that grow on our food sometimes produce toxic substances.
Salt preservation technique is generally used in ________
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Pickles
0%
Jams and jellies
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Fruit drinks
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Both A and B
Explanation
Common salt has been used to preserve meat and fish for ages. Meat and fish are covered with dry salt to check the growth of bacteria. It is also used in pickles to preserve them.
Diseases like polio and chicken pox are caused by ________.
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Bacteria
0%
Fungi
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Viruses
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Worms
Explanation
Both polio and chickenpox are caused by viruses.
Therefore, the correct answer is option C.
Disease caused due to the consumption of contaminated food is ________________.
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Food adulteration
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Food poisoning
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Rancidity
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All of the above
Explanation
Food poisoning as the name suggests is a disease that results from the consumption of contaminated food. Food adulteration means the presence of unwanted materials in the food item which alters the quality of food whereas rancidity means degradation of oil and fats present in the food item.
The undesirable change in a food that makes it unsafe for human consumption is referred to as:
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Food wastage
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Food spoilage
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Food loss
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All of the above
Explanation
Food spoilage is the decrease in the original nutritional value, texture, and flavor of the food. Such food becomes harmful and unsuitable for human consumption. This can happen due to bacterial or fungal action if food is left open for a long time. Food spoilage can be prevented by different methods such as adding preservatives, refrigeration, freezing, boiling, smoking, and canning.
Thus, the correct answer is option B.
Mark the incorrect statement
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Food poisoning could be due to the consumption of food spoilt by some microorganisms.
0%
Microorganims that grow on out food sometimes produce toxic substances.
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Insect make the food poisonous causing serious illness and even death.
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None of these
Explanation
It is very important that we preserve food to prevent it from being spoilt.
Microbes can make the food poisonous causing serious illness and even death.
Food poisoning occurs because of bad food handling practices in:
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Restaurants
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Retail shops
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Home or domestic kitchens
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All of the above
Explanation
Food poisoning occurs due to bad food handling at all the places where it is prepared or stored like restaurants, retail shops, home or domestic kitchens, etc. It occurs due to contamination of food with the toxins of microorganisms.
____________ is the spread of disease from animal to a person.
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Non-communicable
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Genetic
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Communicable
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None of these
Explanation
Communicable diseases spread from one person to another or from an animal to a
person. The spread often happens via airborne viruses or bacteria, but also through blood or
other bodily fluid. The terms infectious and contagious are also used to describe
communicable disease. For example- HIV/AIDS.
Hence the correct option is C.
Tuberculosis is a/an .......... disease.
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Air borne
0%
Non-communicable
0%
Endemic
0%
All of the above
Explanation
Tuberculosis is a primarily an airborne disease. The causative agent for the disease is
Mycobacterium tuberculosis.
The bacteria are spread from person to person in tiny microscopic droplets through the air.
so, the correct answer is option A.
Food poisoning could be due to the consumption of ________.
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Spicy food
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Food spoilt by some microorganisms
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Heavy diet
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All of the above
Explanation
Microbes can make the food poisonous causing serious illness and even death. So, it is very important that we preserve food to prevent it from being spoilt. Microorganisms that grow on our food sometimes produce toxic substances.
Symptoms of food poisoning arise due to
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Presence of bacteria or other microbes in food
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Due to ingestion of toxins contained in food
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Both A and B
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None of these
Explanation
Symptoms of food poisoning are vomiting, nausea, severe pain in abdominal region, diarrhoea and dehydration. It may also cause weakness, fatigue and damage to the nervous system. S
ymptoms of food poisoning arise due to presence of bacteria or other microbes in food or due to ingestion of toxins contained in food.
Choose the correct statement:
a) Food must be properly stored to prevent food poisoning.
b) Food poisoning can occur when food is left unrefrigerated for longer period of time.
c) Mishandling of food can also cause food poisoning.
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a, b
0%
b, c
0%
a, c
0%
All of the above
Explanation
Food must be properly stored to prevent food poisoning. Food poisoning can occur when food is left unrefrigerated for longer period of time.
Mishandling of food can also cause food poisoning.
Lactobacillus
is commonly found in:
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Cake
0%
Curd
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Bread
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All of the above
Explanation
Lactobacillus
is a genus of bacteria, which can convert sugars into lactic acid by means of fermentation. Milk contains a sugar called lactose. The bacteria convert the lactose into lactic acid, which imparts the sour taste to curd. Hence,
Lactobacillus
is usually found in curd
.
So, the correct answer is option C.
Name the diseases caused by protozoa?
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Malaria
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Dysentry
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Both A and B
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Typhoid
Explanation
Protozoa are a group of microorganisms which are unicellular and eukaryotic. Some protozoa are human parasites, causing diseases including malaria, amoebiasis, giardiasis, toxoplasmosis, cryptosporidiosis, trichomoniasis, Chaga's disease, leishmaniasis, sleeping sickness, amoebic dysentery.
So, the correct answer is option C.
Anthrax is a .......... disease.
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Fungal
0%
Bacterial
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Viral
0%
All of the above
Explanation
Anthrax is caused by the bacterium Bacillus anthracis. It mainly spreads from the spores of bacteria. Swelling in the body and reduced milk in cattle's are seen. It is also used as bio-weapon.
So, the correct answer is option B.
What causes communicable diseases?
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Spoiled food item
0%
Unsanitary conditions
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Pathogens
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Dirty objects
Explanation
Explanation: Communicable diseases are caused by pathogens passed from one organism to another. Pathogens are disease-causing organisms. Pathogenic organisms are of five main types: viruses, bacteria, fungi, protozoa, and worms.
Hence the correct option is C.
Raw vegetable grown using sewage water is also responsible for spread of typhoid.
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True
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False
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Ambiguous
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Data insufficient
Explanation
Typhoid is caused due to salmonella typhi. This is been transmitted from and infected patient to healthy individual through faecal oral route. Contaminated food and water leads to transmission for disease.
The symptoms of food poisoning begin within .......... of eating contaminated food.
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10 days
0%
1-2 days
0%
15 days
0%
7 days
Explanation
Food poisoning is the infection caused by the ingestion of food contaminated with bacteria or bacterial infection.
Symptoms of food poisoning begin within 1 to 2 days of eating contaminated food. The symptoms are vomiting, nausea, severe pain in the abdominal region, diarrhoea and dehydration. It may also cause weakness, fatigue and damage to the nervous system.
Thus, the correct answer is option B.
Name the bacteria used in dairy industry.
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Lactobacillus
0%
Bacillus thuringiensis
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E.coli
0%
Both A and B
Explanation
The answer is A.
Lactobacillus
bacteria are used in the dairy industry as these help in fermentation mainly by producing lactic acid and decreasing the pH of milk which causes curdling of milk.
Bacillus
thuringiensis
is mainly used as a biopesticide in agriculture.
E.coli
is found in gut microflora.
__________ are classified as microorganisms.
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Insects
0%
Fungi
0%
Bacteria
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Both B and C
Explanation
Microorganisms are classified into four major groups. These groups are bacteria, fungi, protozoa and some algae. Hence the correct answer is option D.
Fish can be preserved for longer period of time by adding:
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Sugar
0%
Salt
0%
Drying in sunlight
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Both B and C
Explanation
Fish can be preserved by different methods. Salting is one of the oldest methods which is used for preserving fish for a long time. The fish are soaked in salt or brine water. Fish can be dried in sunlight to remove the moisture. The presence of salt and no moisture prevents bacterial contamination. This is how fish do not get degraded easily and are preserved for a longer period of time.
Thus, the correct answer is option D.
Which of the following pairs of microorganisms and diseases is wrongly matched?
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Bacteria - Malaria
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Fungus - Athlete's foot
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Protozoa - Sleeping sickness
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Virus - Tobacco mosaic disease
Explanation
The causative agent for malaria is a parasitic protozoan
Plasmodium
.
The athlete's foot caused by a fungus is
Tinea pedis
.
Trypanosoma brucei
is a species of salivary trypanosome which causes sleeping sickness.
Tobacco mosaic virus causes tobacco mosaic disease in the tobacco plant.
Thus, the correct answer is option A.
How are microorganisms useful to us?
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They are involved in production of chemical fertilizers.
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They are used in production of fireworks.
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They are used in production of soft drinks.
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They are involved in production of antibiotics.
Explanation
The antibiotics are the chemical compounds which is produced by one organism which inhibit the growth of the other organism. The antibiotics can be used for the control of the growth of the bacteria or organisms causing infections. The microorganisms like the bacterial and fungal species are used for the production of the antibiotics which can be used for the control of other microorganisms.
Thus, the correct answer is option D.
Pulse polio oral vaccine is provided only until the age of ___________.
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$$5$$
0%
$$10$$
0%
$$15$$
0%
$$6$$
Explanation
Pulse polio immunization campaign was set up by government of India in the year $$1994$$ to eradicate polio in India. All children under the age of $$5$$ are vaccinated annually against polio virus. Oral vaccine is easy to administer polio vaccine. Raches intestine and prevents multiplication of disease causing virus. The child is then immunized for life.
The bread becomes soft and porous when the yeast cells are mixed in the lump of dough of wheat flour, because:
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Yeast is soft and flour also become soft.
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Yeast produces acetic acid and alcohol which gives softness to the bread.
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Release of CO$$_2$$ makes the bread spongy.
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Yeast produces benzoic acid.
Typhoid is classified as a
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Viral disease.
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Genetic disorder.
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Bacterial disease.
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Protozoan disease.
Explanation
Typhoid fever is caused by
Salmonella typhi
. It is a bacterial, water and food borne disease, which causes gastric upset and fever.
Thus, the correct answer is option C.
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