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NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

Edited By Irshad Anwar | Updated on Sep 20, 2023 07:55 PM IST

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe: Have you ever wondered why stale bread kept in a dark and humid area grows white coloured mesh over it? With Microorganisms friend and foe Class 8 Solutions: you will learn How does the milk with a little curd kept by your mother in a hotter place turn into curd the next morning? All these questions have been discussed in solutions to NCERT Class 8 Science Chapter 2 - Microorganisms Friend and Foe, it is due to the presence of microorganisms. Class 8 Science Chapter 2 deals with the role of microorganisms in our lives. Learning would be easier, and you will learn all the concepts while going through the Class 8 Science Chapter 2 question answer. NCERT Solutions for Class 8 Science provide detailed solutions to each chapter of Class 8 Science. Scroll down to go through the questions and answers given in NCERT Solutions for Class 8 Science Chapter 2.

NCERT Solutions for Class 8 Science Microorganisms Friend and Foe

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NCERT Solutions for Class 8 Science Chapter 2 - Microorganisms: Friend and Foe

Class 8 Science Chapter 2 NCERT Solutions:

What are Microorganisms?

Microorganisms are the smallest organisms that cannot be seen with the naked eye. Now, you must be wondering: if they cannot be seen with the naked eye, then how did we first get to know about them? It was mainly due to the invention of an instrument called the microscope. You will learn about the structure and workings of a microscope in Class 8 Science Chapter 2 - Microorganisms Friend and Foe. you will learn many such concepts in Microorganisms Friend and foe Class 8 NCERT Solutions. These solutions are part of NCERT Solutions for Class 8.

Types of Microorganisms:

There are five groups of microorganisms around us. These include

  1. Bacteria,
  2. Fungi,
  3. Protozoa
  4. Algae
  5. Viruses.

Microorganisms friend and foe Class 8 Solutions explains that Among the above-given microorganisms, viruses are different from the rest. How? You will learn all about in Chapter 2 Science Class 8 - Microorganisms Friend and foe of NCERT. You can also check out the NCERT Solutions (classes 6 to 12) for other chapters in science or even for other subjects by using the given links on this page.

Microorganisms: Friend and Foe Class 8 Science NCERT Textbook Questions Answers

Class 8 Science Chapter 2 question answer are given below:

Class 8 Microorganisms Friend and Foe NCERT Solutions:

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 air and enhance fertility of soil.
(c) Alcohol is produced with the help of Yeast .
(d) Cholera is caused by Bacteria .

Microorganisms Friend and Foe Class 8 Solutions

Q.2.(a) Tick the correct answer. Yeast is used in the production of (i) sugar

(ii) alcohol

(iii) hydrochloric acid

(iv) oxygen

Answer:

(a) Yeast is used in the production of (ii) Alcohol

Microorganisms Friend and Foe Class 8 NCERT Solutions:

Q.2(b). Tick the correct answer

The following is an antibiotic

(i) Sodium bicarbonate

(ii) Streptomycin

(iii) Alcohol

(iv) Yeast

Answer:

(b) The following is an antibiotic (ii) Streptomycin

Class 8 Science Chapter 2 Question Answer:

Q.2(c). Tick the correct answer

Carrier of malaria-causing protozoan is

(i) female Anopheles mosquito (ii) cockroach

(iii) housefly (iv) butterfly

Answer:

(c) Carrier of malaria-causing protozoan is (i) female Anopheles mosquito

Class 8 Science Chapter 2 NCERT Solutions:

Q.2(d). The most common carrier of communicable diseases is

(i) ant (ii) housefly (iii) dragonfly (iv) spider

Answer:

(d) The most common carrier of communicable diseases is (ii) housefly.

Class 8 Microorganisms Friend and Foe NCERT Solutions:

Q.2(e). Tick the correct answer

The bread or idli dough rises because of

(i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading

Answer:

(e) The bread or idli dough rises because of (iii) The growth of yeast cells.

Microorganisms Friend and Foe Class 8 Questions and Answers:

Q.2(f). Tick the correct answer

The process of conversion of sugar into alcohol is called

(i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection

Answer:

(f) The process of conversion of sugar into alcohol is called (iii) Fermentation

NCERT Solutions for Class 8 Science Chapter 2 - Microorganisms Friend and Foe

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:
Column A
Column B
Bacteria
Causing Cholera
Rhizobium
Fixing nitrogen
Lactobacillus
Setting of curd
Yeast
Baking of bread
A protozoan
Causing malaria
A virus
Causing AIDS


Class 8 Microorganisms Friend and Foe NCERT Solutions

Q. 4. Can microorganisms be seen with the naked eye? If not, how can they be seen?

Answer:

No, the microorganisms cannot be seen with the human naked eye because they are too small to be seen. microorganisms can be seen with the help of a scientific instrument called microscope.

Example- fungus on bread.

Microorganisms Friend and Foe Class 8 Solutions:

Q. 5. What are the major groups of microorganisms?

Answer:

The major groups of microorganisms are as follows-

(i) Bacteria- unicellular organisms. most common examples of bacteria are Salmonella typhi, Rhizobium, Mycobacterium etc. Typhoid and tuberculosis (TB) are bacterial diseases.

(ii) Fungi- Multicellular organisms which feed on dead and deaying matter. Bread mould is common examples.

(iii) Protozoa- Unicellular organisms wihich are mostly parasitic. Organisms like Amoeba, Plasmodium etc are under this category. Dysentery and malaria are caused by protozoans.

(iv) Virus- Acellular organisms which reproduce only inside the cells of the host organism. These cause diseases like chicken pox and polio.

(v) Algae- They are unicellular or multicellular organism. Spirogyra, Chlamydomonas, Ulva are some of the examples of algae.

Q6. Name the microorganisms which can fix atmospheric nitrogen in the soil.

Answer:

The microorganism that can fix atmospheric nitrogen in the soil are bacteria such as Rhizobium , and blue-green algae. These converted nitrogenous compounds can be easily used by plants for the plant protein synthesis and other purposes.

Q 7. Write 10 lines on the usefulness of microorganisms in our lives.





Answer :

Microorganisms are useful for us in the following ways-

  • Microorganisms are used to increase the fertility of the soil by fixing the atmospheric nitrogen with the help of blue-green algae and Rhizobium.
  • Antibiotics which are obtained from microorganisms are used to control the diseases.
  • There are some bacteria which can turn nitrogen compounds found in the soil into nitrogen gas which is further released into the environment.
  • Bacterium Lactobacillus reproduces in milk and promotes the formation of curd.
  • Microorganisms especially yeast can be used for the industrial production of alcohol, wine and acetic acid (vinegar).
  • Microbes are used to reduce pollution. example- bacteria and fungi break down the dead bodies and excreta to form inorganic compounds which are absorbed by plants
  • Yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume. Thus they have a use in making of bread.


Microorganisms Friend and Foe Class 8 NCERT Solutions

Q. 8. Write a short paragraph on the harmful effects of microorganisms.

Answer:

The harmful effects of microorganisms are given below-

  • Microorganisms cause diseases in humans as well as animals. For example cholera and TB are caused by bacteria in humans.
  • In plants also diseases are caused by microorganisms. For example, citrus canker in plants is caused by bacteria and rust of wheat is caused by fungi.
  • Food poisoning is also caused by the microorganisms that spoils our food by producing some toxic substances. For example- when the bread is left in under moist condition gets spoilt by fungus.

Class 8 Science Chapter 2 Question Answer

Q. 9. What are antibiotics? What precautions must be taken while taking antibiotics?

Answer:

Antibiotics- These are medicines that kill or stop the growth of the disease-causing microorganisms. There are a lot of antibiotics which are produced with the help of bacteria and fungi. Streptomycin, tetracycline and erythromycin are some of the commonly known antibiotics which are made from fungi and bacteria.

Precautions that must be taken while using antibiotics-

  • Antibiotics must be taken obly on the prescrition of a doctor.
  • must finish the course prescribed by the doctor.
  • An antibiotic should be taken in the right amount only. Antibiotics taken unnecessarily may kill beneficial bacteria in the body.

Class 8 Science Chapter 2 NCERT Solutions

Q. 10. What precautions must be taken while taking antibiotics?

Answer:

Those medicines kill or stop the growth of the disease-causing microorganisms are called antibiotics. Antibiotics are
being produced from bacteria and fungi.

Precaution to be taken while using antibiotics-

  • antibiotics should be taken only on the advice of a qualified doctor.
  • must finish the course prescribed by the doctor.
  • An antibiotic should be taken in the right amount. antibiotics taken unnecessarily may kill beneficial bacteria in the body.

NCERT Solutions for Class 8 Science Chapter 2 - Microorganisms Friend and Foe

To effectively prepare for their exams, students must regularly practice these solutions. Students can fully comprehend the topic with the help of these solutions. If they want to take biology in higher secondary schools, they should read the chapter Microorganisms Friend and Foe. Students in the 8th standard should carefully review the NCERT Solutions for Class 8 Science Chapter 2. These responses will assist them in mastering the ideas covered in the chapter Microorganisms: Friend and Foe, which are listed above. Subject matter experts developed the NCERT Solutions for Class 8 in accordance with the most recent CBSE syllabus

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

Important topics in Class 8 Science Chapter 2 Microorganisms Friend and Foe:

Section Name
Topic Name
2Microorganisms Friend and Foe
2.1Microorganisms
2.2Where do Microorganisms Live?
2.3Microorganisms and Us
2.4Harmful Microorganisms
2.5Food Preservation
2.6Nitrogen Fixation
2.7Nitrogen cycle

Highlights of NCERT Solutions for Class 8 Science Chapter 2:

The key features of Class 8 Microorganisms Friend and Foe NCERT Solutions:

  • Now that you know the Microorganisms Friend and Foe Solutions and have understood the topics well, it's time to practice the Class 8 Science Chapter 2 question answer.
  • Check previous year's questions from the exam and practice Microorganisms Friend and Foe Class 8 Questions and Answers
    to know your preparation levels.
  • NCERT Solutions for Class 8 is the base of your learning for further classes.
  • Class 8 Science Chapter 2 NCERT Solutions will also boost your knowledge.
  • NCERT solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe will also help you to understand all the concepts easily.
  • Class 8 Science Ch 2 question answer are created by experienced subject matter experts.
  • NCERT Solutions for Class 8th Science aims to ease the learning and make it more interesting to build foundation strong.
  • Class 8 chapter 2 science is important to clear all basic concepts related to microoganisms.
  • The Science Chapter 2 Class 8 Solutions are developed by thE experienced subject experts and are totally reliable.
  • Class 8 Science Chapter 2 PDF are easy to download and use offline.

NCERT Solutions For Class 8th Science: Chapter-wise

NCERT Solutions For Class 8th: Subject-wise

Also, Check NCERT Books and NCERT Syllabus here


We hope you will ace your examination with the help of NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe.

Frequently Asked Question (FAQs)

1. Whether the chapter Microorganisms Friends and Foe is useful for higher studies

Yes, the concepts studied in the chapter are useful for higher studies. The class 12 NCERT topic biology and human welfare is a continuation of this chapter. This chapter can be a foundation for the NEET exam. 

2. What are the topics covered in NCERT Class 8 Science chapter 2 ?

Here are the topics covered in NCERT Class 8 Science chapter 2

  •   Microorganisms   
  •    Where do microorganisms live   
  •    Microorganisms and us   
  •    Harmful microorganisms   
  •    NItrogen fixation   
  •    Nitrogen cycle   
3. How many questions in NCERT Class 8 Science chapter 2 exercise?

There are 10 questions in NCERT Class 8 Science chapter 2 exercise

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Get answers from students and experts

A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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