NCERT Class 8 Science Chapter 2 Microorganisms : Friend and Foe Extra Questions

NCERT Class 8 Science Chapter 2 Microorganisms : Friend and Foe Extra Questions and Answers

Microorganisms : Friend and Foe Extra Questions

Class 8 Science Chapter 2 Extra Questions and Answers – Microorganisms : Friend and Foe. Here in this Page Class VII Students can Learn Extra Questions & Answer 2nd Chapter Science fully Inside.

We Provided Here Microorganisms : Friend and Foe Science Chapter 2 Long Answer Type Question, Very Short Type Questions (VSA) / MCQ Type Questions, Short Type Questions (SA).

Class 8 Science Chapter 2 Extra Question with Answer – Microorganisms : Friend and Foe

Science Chapter 2 Microorganisms : Friend and Foe Class 8 Inside 5 Marks, 3 marks, 2 Marks & And 1 Marks Important Questions and Answers.

1)  Fill in the blanks:

a) The disease like ___ is caused by viruses. (Polio)

b) Raw mangoes are preserved by ___. (Salt)

c) Milk is turned into curd by ___. (Bacteria)

d) ___ is a preservative. (Salt)

e) The disease-causing microorganisms are called ___. (Pathogens)

f) Cholera can spread from an infected person to a healthy person through ___. (Food)

g) The process of heating, chilling and storing milk to prevent the growth of microbes, is called ___. (Pasteurization)

2)  Multiple choice questions:

a) Malaria is caused by ___?

a) Protozoa b) Bacteria c) Virus

Ans. a) Protozoa

b) The process of conversion of sugar into alcohol is known as ___?

a) Preservation b) Fermentation

Ans. b) Fermentation

c) Typhoid can spread from an infected person to a healthy person through ___?

a) Air b) Food c) Water

Ans. c) Water

d) Rust of wheat can spread through ___?

a) Seeds b) Insect

Ans. a) Seeds

e) Chicken pox can spread from an infected person to a healthy person through ___?

a) Contact b) Water c) Food

Ans. a) Contact

f) ___ is a dangerous human and cattle disease caused by a bacterium?

a) Malaria b) Polio c) Anthrax

Ans. c) Anthrax

g) Yellow vein mosaic of ladies’ finger is a plant disease which is caused by _____ microbe?

a) Bacteria b) Virus c) Fungi

Ans. b) Virus

3)  Answer the following questions:

a) Name two diseases those are caused by virus.

Ans. Two diseases those are caused by virus are polio and foot and mouth disease of cattle.

b) State the uses of yeast.

Ans. Yeast is used for making breads, pastries and cakes and also used for commercial production of alcohol and wine.

c) Name two diseases those are caused by bacteria.

Ans. Two diseases those are caused by bacteria are tuberculosis and Citrus canker.

d) What percentage nitrogen gas is found in the atmosphere? Write one use of nitrogen.

Ans. 78% nitrogen gas is found in the atmosphere.

Nitrogen is used for the synthesis of plant proteins and other compounds.

e) What are microorganisms? What are the major groups of microorganisms?

Ans. There are some living organisms around us which are not visible to the unaided eye, are called microorganisms.

The major groups of microorganisms are bacteria, fungi, protozoa and some algae.

f) What are antibiotics? State the uses of antibiotics?

Ans. The medicines that are used to kill or stop the growth of the disease-causing microbes, are called antibiotics.

The uses of antibiotics are,

I.)  Antibiotics are used to cure a variety of diseases.

II.)  These are even mixed with the feed of livestock and poultry to check microbial infection in animals.

III.)  They are also used to control many plant diseases.

4)  Match the items of column I with the information of column II:

           Column I

Column II

a)  Spoilage of pickles

nitrogen

1) are used to increase soil fertility by fixing

 

b)  Jams 2)  The process of conversion of sugar into alcohol
c)  Malaria 3) Polio can spread through
d)  Fungi 4) preserved by oil
e)  Bacteria 5) preserved by sugar
f)  Fermentation 6) caused by protozoa
g)  Air 7) Which causes rust of wheat is a plant disease

Ans. a) – 4), b) – 5), c) – 6), d) – 7), e) – 1), f) – 2), g) – 3).

5)  Mark your answer as per the codes provide below:

a) A: One should not let water collect anywhere, in coolers, tires, flower pot, etc.

R: All mosquitoes breed in water.

I.)  Both A and R are true and R is the correct explanation of A.

II.)  Both A and R are true but R is not the correct explanation of A.

III.)  A is true but R is false.

IV.)  A is false but R is true.

V.) Both A and R are false.

Ans. I. Both A and R are true and R is the correct explanation of A.

b) A: It is very important that we preserve food to prevent it from being spoilt.

R: Microorganisms that grow on our food sometimes produce toxic substances. These make the food poisonous causing serious illness and even death.

I.)  Both A and R are true and R is the correct explanation of A.

II.)  Both A and R are true but R is not the correct explanation of A.

III.)  A is true but R is false.

IV.)  A is false but R is true.

V.)  Both A and R are false.

Ans. I. Both A and R are true and R is the correct explanation of A.

6)  There are some insects and animals which act as carriers of disease-causing microbes. Housefly is one such carrier. The flies sit on the garbage and animal excreta. Pathogens stick to their bodies. When these flies sit on uncovered food they may transfer the pathogens. Whoever eats the contaminated food is likely to get sick. So, it is advisable to always keep food covered. Avoid consuming uncovered items of food. Another example of a carrier is the female Anopheles mosquito which carries the parasite of malaria. Female Aedes mosquito acts as carrier of dengue virus.

a) Female ___ mosquito carries the parasite of malaria?

a) Anopheles b) Aedes

Ans. a) Anopheles

b) Female ___ mosquito acts as carrier of dengue virus. (Aedes)

c) ___ is a carrier of disease-causing microbes. (Housefly)

d) Why it is advisable to always keep food covered?

Ans. It is advisable to always keep food covered because the flies sit on the garbage and animal excreta and pathogens stick to their bodies. When these flies sit on uncovered food they may transfer the pathogens. Whoever eats the contaminated food is likely to get sick.

 

More Extra Questions and Answers

Section 1

Q.1) Fill in the blanks

1) Bacteria, fungi protozoa and Algae classified as four major groups of microorganism.

2) Diseases like dysentery and malaria are caused by protozoa.

3) Bacteria Promotes the formation of curd.

4) Medicines used to kill or stop the growth of disease causing microorganisms are called as antibiotics.

5) When a disease carrying microbe enters our body, the body produces Antibodies.

6) Common salt has been used to preserve meat and fish for ages.

7) Our atmosphere has 78%nitrogen gas

 

Q.2) Define the following

1.) Communicable disease

Ans: Microbial disease that can spread from an infected person to a healthy person through air, water, food physical contact are called communicable diseases.

2.) Fermentation

Ans : The process of conversion of sugar into alcohol is called as fermentation.

 

In case you are missed :- NCERT Extra Questions for Crop Production And Management

 

3.) Antibiotics

Ans : The medicines used to kill or stop the growth of disease causing microorganisms is called as antibiotics.

4.) Pathogens

Ans : Microorganisms that causes disease in human beings plants and animals such disease causing microorganisms are called as pathogens.

5.) Microorganisms

Ans :Living organisms around us which cannot be seen with the naked eye is called as microorganisms.

 

Q.3) Answer the following

1.) How are microorganism classified?

Ans:Microorganisms are classified into four major groups such as bacteria, fungi, protozoa, algae.

2.) What is the use of microorganism ?

Ans :Microorganisms are used for the production of alcohol.

3.) Where can we find microorganisms ?

Ans :Microorganisms are found in air, water and bodies of plants and animals

4.) Why oil and vinegar are used to prevent Pickles ?

Ans :Use of oil and vinegar prevents this spoilage of pickle because bacteria cannot live in this environment.

5.) Why does the milk that comes in packets does not get spoiled?

Ans :The milk that comes in packet does not get spoiled because it is pasteurised.

 

Q.4) Write notes on the following

1.) Food poisoning

Ans :i) a) Food poisoning could be due to consumption of food which is spoiled by microorganisms

b) Microorganisms grow on the food and produce toxic substance

c) This substance makes the food poisonous resulting in food poisoning

 

2) Microorganism and its uses

i) a) Microorganismsare tiny organisms which cannot be seen with naked eyes.

b) Micro-organisms are classified into four major groups such as bacteria, fungi, protozoa and algae.

ii) Uses of microorganism

  • Microorganisms are used for the production of alcohol
  • Microorganisms are used in preparation of curd, bread and cake.
  • Microorganisms are used in production of antibiotics

iii) Harmful microorganisms

  • harmful microorganisms which causes disease in human beings, plants and animals are called as pathogens
  • They get transmitted by direct contact or an carrier.Kn
  • Harmful microorganisms spoil the food and causes food poisoning.
  • Some harmful microorganisms spoiled food, clothing and leather.

 

3) Write the preventive measures for the following

a) Tuberculosis

Ans : Keep the patient in isolation, belongings of the patient away from others. get vaccinated at given time.

b) Typhoid

Ans : Maintain personal hygiene and good sanitary habits drink boiled water. get vaccinated on time.

c) Malaria

Ans :Use mosquito net. spray insecticide uncontrolled breeding of mosquitoes. do not allow the water to collect in the surroundings.

d) Chicken pox

Ans :Keep the patient away from others and let not touch the things .keep the person in complete isolation.

E) Hepatitis A

Ans : drink boiled water and get vaccinated at given time.

 

4.) Write a note on nitrogen cycle

Ans : a) our atmosphere content 78% nitrogen gas

b.) Nitrogen is one of the essential constituant for all living organisms and nitrogen cannot be taken directly by plants and animals.

c) Certain bacteria and algae are present in the soil to fix the nitrogen and convert into nitrogen compounds

d) once the nitrogen is converted into usable compounds it can be utilised by plants and animals.

e.) During this process some part of the nitrogen gas goes back to the atmosphere as a result the amount of nitrogen remains more or less

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Updated: April 5, 2023 — 11:32 am

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