NCERT Solutions For Class 8 Science Chapter 2- Microorganism Friend And Foe Solutions Pdf Download
NCERT Solutions For Class 8 Science Chapter 2 Microorganism Friend And Foe Solutions deals with Microorganisms, the Classification of Microorganisms and the Use of Microorganisms. These Class 8 Science Chapter 2 solutions will help you in scoring good marks as they cover important concepts in different patterns like MCQs and short answer questions, worksheets and more. NCERT Solutions For Class 8th Science Ch 2 helps students in many ways. Class 8 Science Chapter 2 Question and Answer are designed by our subject expert team.
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NCERT Solutions For Class 8 Science Chapter 2 Overview
Microorganism Friend And Foe Solutions cover the topics of Algae, Antibiotics, Bacteria, Carrier, Communicable Diseases, Fermentation, Fung, Lactobacillus, Microorganisms, Nitrogen Cycle, Nitrogen Fixation, Pasteurisation, Pathogen, Preservation, Protozoa, Rhizobium, Vaccine, Virus, Yeast for a detailed study you can check Class 8 Science Chapter 2 notes.
Class 8 Science Chapter 2 Question and Answer
Q 1. Fill in the blanks.
(a) Microorganisms can be seen with the help of a ____________.
(b) Blue-green algae fix __________ directly from air and enhance fertility of soil.
(c) Alcohol is produced with the help of __________.
(d) Cholera is caused by __________.
Answer:
(a) Microorganisms can be seen with the help of a Microscope.
(b) Blue-green algae fix Nitrogen directly from the air and enhance the fertility of the soil.
(c) Alcohol is produced with the help of Yeast.
(d) Cholera is caused by Bacteria- Vibrio cholera.
Q 2. Tick the Correct Answer.
(a) Yeast is used in the production of
(i) sugar (ii) alcohol (iii) hydrochloric acid (iv) Oxygen
(b) The following is an antibiotic
(i) Sodium bicarbonate (ii) Streptomycin (iii) Alcohol (iv) Yeast
(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) butterfly
(d) The most common carrier of communicable diseases is
(i) Ant (ii) housefly (iii) dragonfly (iv) spider
(e) The bread or idli dough rises because of
(i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading
(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection
Answer:
a) (ii) alcohol
b) (ii) Streptomycin
c) (i) female Anopheles mosquito
d) (ii) housefly
e) (iii) growth of yeast cells
f) (iii) fermentation
Q 3. Match the Organisms in Column A With their action in Column B.
| A | B |
| (i) Bacteria | (a) Fixing nitrogen |
| (ii) Rhizobium | (b) Setting of curd |
| (iii) Lactobacillus | (c) Baking of bread |
| (iv) Yeast | (d) Causing malaria |
| (v) A protozoan | (e) Causing cholera |
| (vi) A virus | (f) Causing AIDS |
| (g) Producing antibodies |
Answer:
| A | B |
| (i) Bacteria | (e) Causing cholera |
| (ii) Rhizobium | (a) Fixing nitrogen |
| (iii) Lactobacillus | (b) Setting of curd |
| (iv) Yeast | (c) Baking of bread |
| (v) A protozoan | (d) Causing malaria |
| (vi) A virus | (f) Causing AIDS |
Q 4. Can Microorganisms be seen with the Naked eye? If not, How can they be seen?
Answer:
Microorganisms cannot be seen by the naked eye because they are very small. They can be seen by using a microscope.
Q 5. What are the Major Groups of Microorganisms?
Answer:
Microorganisms include
- Bacteria
- Fungi
- Protozoans
- Algae
- Viruses
Viruses, though different from the above-mentioned living organisms, are considered microbes.
Q 6. Name the Microorganisms Which can fix Atmospheric Nitrogen in the Soil.
Answer:
Rhizobium Microorganisms can fix Atmospheric Nitrogen in the Soil
Q 7. Write 10 Lines on the Usefulness of Microorganisms in our Lives.
Answer:
The uses of microorganisms are listed below
- Microorganisms are used in the preparation of curd, bread and cake.
- The bacterium, lactobacillus Microorganisms converts milk into curd.
- Microorganisms have been used for the production of alcohol, wine and acetic acid(vinegar).
- They are also used in cleaning up the environment. For example, organic wastes (vegetable peels, remains of animals, faeces, etc.) are broken down into harmless and usable substances by bacteria.
- Bacteria are used in the preparation of medicines.
- Bacteria are also involved in the making of cheese, pickles and many other food items.
- Antibiotics are produced from bacteria and fungi.
- Some bacteria are able to fix nitrogen from the atmosphere to enrich the soil with nitrogen and increase its fertility.
- They are also used to control many plant diseases.
- Microorganisms decompose dead organic waste of plants and animals to convert them into simple substances. These substances are again used by other plants and animals. Thus, microorganisms can be used to degrade harmful and smelly substances and thereby clean up the environment.
- Some of the microorganisms grow in our food and cause food poisoning.
Q 8. Write a Short Paragraph on the Harmful Effects of Microorganisms.
Answer:
Harmful Microorganisms are microorganisms which are harmful to us in many ways.
- microorganisms cause diseases in human beings, plants and animals. Such disease-causing microorganisms are called pathogens Ex; Cholera in humans is caused by bacteria called Vibrio cholera..
- Some microorganisms spoil food, clothing and leather.
- Microorganisms are responsible for food poisoning.
- In animals, the virus causes foot and mouth diseases.
Q 9. What are Antibiotics? What Precautions Must be Taken While Taking Antibiotics?
Answer:
Chemical agents that kill or stop the growth of disease-causing microorganisms are called antibiotics. Antibiotics should be taken only on the advice of a qualified doctor.
Class 8 Science Chapter 2 KeyWords Solutions
NCERT Solutions For Class 8 Science Chapter 2 KeyWords Definition
Algae: A group of plants which is mostly aquatic. They are autotrophs (i.e., have chlorophyll). Their body is not divided into root, stem and leaf.
Antibiotics: Chemical agents that kill or stop the growth of disease-causing microorganisms are called antibiotics.
Bacteria: Bacteria are single-celled microorganisms. They can be seen only under a microscope.
Carrier: The organisms which carry the diseased from an ill person to a healthy person are called carriers. For example, the female Anopheles mosquito.
Communicable Diseases: The microbial diseases that can be spread from an infected person to a healthy person through the air, water, food or physical contact are called communicable diseases.
Fermentation: The process of conversion of sugar into alcohol by yeast is called fermentation.
Fungi: Fungi are non-green plants. They cannot synthesize their own food. They may be unicellular or multicellular.
Lactobacillus: Lactobacillus is the bacteria responsible for the formation of curd from milk.
Microorganisms: These are organisms that are too small and are not visible to the naked eye. These include a virus, bacteria, fungi, protozoa and some algae.
Nitrogen Cycle: A process (cycle) by which the amount of nitrogen remains constant in the atmosphere is known as the nitrogen cycle.
Nitrogen Fixation: The atmospheric nitrogen is fixed by bacteria and blue-green algae present in the soil and converted into compounds of nitrogen called Nitrogen Fixation.
Pasteurisation: The process in which milk is heated to about 70°C for 15 to 30 seconds and then suddenly cooled.
Pathogen: Disease-causing microorganisms are called pathogens.
Preservation: Prevention of spoiling food from the action of microorganisms is called food preservation.
Protozoa: Protozoa are unicellular animals. Protozoans cause serious diseases like dysentery and malaria.
Rhizobium: Rhizobium is a bacterium which lives in the root nodules of leguminous plants. This helps in the fixation of nitrogen.
Vaccine: The substance which is injected to trigger the body to develop its own defence (by producing antibodies) is called a vaccine.
Virus: They reproduce only inside the host organism: bacterium, plant or animal cell. They are considered as connecting links between living and non-living.
Yeast: Yeast is a unicellular fungus.
Class 8 Science Chapter 2 Extra Question
NCERT Solutions For Class 8 Science Chapter 2 Extra Question
Class 8 Science Chapter 2 MCQ
NCERT Solutions For Class 8 Science Chapter 2 MCQ
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