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

 

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe: Have you ever wondered why a stale bread kept in the dark and humid area grows white colored mesh over it?  How the milk with a little curd kept in a hotter place by your mother turn into curd next morning? All these questions have been discussed in CBSE NCERT solutions for class 8 science chapter 2 Microorganisms Friends and Foe, it is due to the presence of microorganisms. This chapter deals with the role of microorganisms in our lives. After studying the chapter and solutions of NCERT for class 8 science chapter 2 Microorganisms Friends or Foe thoroughly, you will be able to attempt the exercise given in the textbook. Learning would be easier if you have CBSE NCERT solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe within your reach. You can also check out the solutions of NCERT for other chapters in science or even for other subjects by using the given links on this page.

Exercise Questions

 

  • What are microorganisms?

Microorganisms are the smallest organisms that can not be seen with naked eyes. Now, must be wondering that if they can not be seen with naked eyes 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 get to know about the structure and working of a microscope in NCERT grade 8 science chapter 2 microorganisms friends and foe.

  • Types of microorganisms

There are five groups of microorganisms around us. These include

  1. Bacteria,

  2. Fungi,

  3. Protozoa

  4. Algae

  5. Viruses.

Among the above-given microorganisms, viruses are different from the rest. How? You will learn in class 8 science chapter 2.

NCERT Class 8 Science Chapter 2 Microorganisms Friend and Foe- Topics

The contents of NCERT science class 8 Chapter 2 are divided into certain topics and subtopics which are mentioned hereunder.

2.1 Microorganisms

2.2 Where do microorganisms live

2.3 Microorganisms and us

2.4 Harmful microorganisms

2.5 NItrogen fixation

2.6 Nitrogen cycle

Q. Why do teachers keep telling us not to let water collect anywhere in our surroundings?

Ans. The teachers keep telling us to not let water collect anywhere because this water may act as a breeding site for insects that can cause diseases like dengue, malaria etc.

Q. The milk that comes in packets do not get spoiled because it is pasteurised. What do you understand by pasteurized milk?

Ans. The packeted milk is boiled at high-temperature for 15 to 30 seconds to kill the microbes present in it. This milk is called pasteurized milk and it does not get spoiled. 

So, like these questions, you can solve more for examination purpose. 

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

Microorganisms: Friend and Foe Excercise:

 

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.

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.

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.

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.

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.

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 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

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.

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.


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-Wise

Chapter -1  

      NCERT Solutions For Class 8 Science Chapter 11- Force and Pressure

Chapter -2

    NCERT solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe

Chapter-3

Solutions of NCERT for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

Chapter-4

NCERT solutions for class 8 science chapter 4 Materials: Metals and Non-Metals

Chapter-5

CBSE NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum

Chapter-6

NCERT solutions for class 8 science chapter 6 Combustion and Flame

Chapter-7

Solutions of NCERT for Class 8 Science Chapter 7 Conservation of Plants and Animals

Chapter-8

NCERT solutions for class 8 science chapter 8 Cell: Structure and Function

Chapter-9

CBSE NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animals

Chapter-10

NCERT solutions for class 8 science chapter 10 Reaching the age of adolescence

Chapter-11

Solutions of NCERT for Class 8 Science Chapter 11 Force and Pressure

Chapter-12

CBSE NCERT Solutions for Class 8 Science Chapter 12 Friction

Chapter-13

NCERT solutions for class 8 science chapter 13 Sound

Chapter-14

Solutions of NCERT for Class 8 Science Chapter 14 Chemical Effects of Electric Current

Chapter-15

NCERT solutions for class 8 science chapter 15 Some Natural Phenomena

Chapter-16

CBSE NCERT Solutions for Class 8 Science Chapter 16 Light

Chapter-17

NCERT solutions for class 8 science chapter 17 Stars and The Solar System

Chapter- 18

Solutions of NCERT for Class 8 Science Chapter 18 Pollution of Air and Water

NCERT Solutions For Class 8: Subject-Wise

 How to use NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe?

  • Now that you know the solutions of NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friends and Foe and have understood the topics well, its time to put them to practice
  • Check previous year questions from the board exam and see if you can apply the CBSE NCERT solutions of class 8 to them and know your preparation levels.
  • If you have not really scored well, it's time to practice a bit more. If you have been able to answer the questions, it's time to move to NCERT solutions for class 8 science chapter 2 Microorganisms Friends and Foe as your aim is to really do well in those board exams.
  • Have any questions for which you could not find the NCERT solutions? Well, go ahead and ask them here. You will hear from our experts who will give you not just the solutions but also examples if needed. 

 

 

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