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

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Last updated date: 29th Mar 2024
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MVSAT 2024

NCERT Solutions for Class 8 Science Chapter 2| Free PDF Download

Vedantu goes over the NCERT answers for Class 8 Science Chapter 2 in depth. Vedantu is a publicly available NCERT solution pdf created by professionals that covers all of the chapters' important concepts, NCERT questions, and activities. Protozoa, Bacteria, Fungi, and Algae dominate Chapter 2 of Class 8 Science. Viruses and vaccinations are also discussed in the chapter.


Class:

NCERT Solutions For Class 8

Subject:

Class 8 Science

Chapter Name:

Chapter 2 - Microorganisms: Friend and Foe

Content Type:

Text, Videos, Images and PDF Format

Academic Year:

2023-24

Medium:

English and Hindi

Available Materials:

Chapter Wise

Other Materials

  • Important Questions

  • Revision Notes


The NCERT Solutions pdf provided by Vedantu consists of all the key topics mentioned above. Also, the solutions are curated by expert educators with step-wise solutions. These solutions are specifically aimed to help students develop a better understanding of the topic.


Download the NCERT Solutions for Class 8 Science Chapter 2 and ace your upcoming examinations! 


Topics Covered in NCERT Solutions Class 8 Science Chapter 2

The following are the important topics that are discussed in Chapter 2 of the Class 8 Biology syllabus.

  • Introduction to microbes

  • Introduction to different types of microbes

  • Introduction of virus

  • Where do microbes live?

  • Commercial use of microbes

  • Medicinal use of microbes

  • Vaccine

  • Microbes' role in increasing soil fertility

  • Pathogens

  • The disease-causing microorganisms in humans

  • The disease-causing microorganisms in plants

  • The disease-causing microorganisms in animals

  • Food preservation

  • Nitrogen fixation

 

Key Points of Microorganisms Friend and Foe at a Glance

Let us look at some important points that are discussed in the chapter.

  • Microbes are tiny creatures that cannot be seen with naked eyes.

  • Protozoa, bacteria, fungi, and algae are the classification of microbes.

  • Viruses are acellular creatures that possess nucleic acid but cannot replicate without a host cell.

  • Microbes are both harmful and helpful depending on their type.

  • Some microbes can be used to make medications and alcohol commercially. 

  • Some microbes clean up the environment by decomposing organic waste and dead plants and animals into simple compounds. 

  • Some microbes can cause diseases that are called pathogens.

  • Dysentery and malaria are two devastating diseases caused by protozoa.

  • A vaccination is a biological preparation that delivers disease-specific active acquired immunity.

  • Leguminous plants' root nodules are home to a variety of microorganisms. 

  • The microbes residing in such legumes are involved in nitrogen fixation.

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

1. Fill in the blanks:

a. Microorganisms can be seen with the help of a ______.

Ans: Microscope

b. Blue-Green Algae fix ______ directly from the air to enhance the fertility of the soil.

Ans: Nitrogen

c. Alcohol is produced with the help of _________.

Ans: Yeast

d. Cholera is caused by _________.

Ans: Bacteria


2. Tick the correct answer:

a. Yeast is used in the production of

i. Sugar

ii. Alcohol 

iii. Hydrochloric acid 

iv. Oxygen

Ans: (ii) Alcohol.

Yeast is used in the production of alcohol, which converts sugar into ethanol and carbon dioxide. 


b. Which of the following is an antibiotic?

i. Sodium bicarbonate

ii. Streptomycin

iii. Alcohol

iv. Yeast 

Ans: (ii) Streptomycin

Streptomycin is an antibiotic, sodium bicarbonate is an antacid, alcohol is a drug, and yeast is a fungus.


c. The carrier of Malaria-causing protozoan is

i. Female Anopheles mosquito

ii. cockroach

iii.  Housefly

iv. Butterfly 

Ans: (i) Female Anopheles mosquito

Female Anopheles mosquito carries Malaria-causing protozoan which causes Malaria in humans.


d. The most common carrier of communicable diseases is

i. Ant

ii. Housefly 

iii. Dragonfly

iv. Spider 

Ans: (ii) Housefly

Ant, dragonflies, and spiders do not carry any diseases.


e. The bread or idli dough rises because of

i. Heat

ii. Grinding

iii. Growth of yeast cells 

iv. Kneading 

Ans: (iii) Growth of yeast cells 

The yeast cells are microorganisms that grow, respire, and release carbon dioxide, which is responsible for raising the bread or idli dough.


f. The process of conversion of sugar into alcohol is called

i. Nitrogen fixation

ii. Moulding

iii. Fermentation

iv. Infection 

Ans: (iii) Fermentation 

The fermentation process involves the conversion of sugar into alcohol.

3. Match the organisms in column I with their action in column II.

Column I

Column II

1. Bacteria

2. Rhizobium

3. Lactobacillus

4. Yeast

5. A protozoan

6. A virus

a. Fixing of nitrogen

b. Setting of curd 

c. Baking of bread

d. Causing malaria

e. Causing Cholera

f. Causing aids

Ans: 

Column I

Column II

1. Bacteria

2. Rhizobium

3. Lactobacillus

4. Yeast

5. A protozoan

6. A virus

    e. Causing cholera

     a. Fixing of nitrogen

     b. Setting of curd

     c. Baking of bread

     d. Causing malaria

     f. Causing aids

  1. Bacteria is a microorganism that causes a disease called cholera.

  2. Rhizobium is a bacteria that is useful in the fixation of atmospheric nitrogen in the soil.

  3. Lactobacillus produces lactic acid by converting sugar that coagulates and partially digest the milk protein and giving rise to curd.

  4. The yeast cells are microorganisms that grow, respire and release carbon dioxide, which is responsible for raising and baking bread.

  5. A protozoan is a microorganism carried by female anopheles mosquitoes which causes malaria.

  6. A virus named HIV causes AIDS

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

Ans: No, microorganisms cannot be seen with the naked eye as they are minute organisms. But microorganisms can be seen through a microscope. 


5. What are the major groups of microorganisms?

Ans: There are five major groups of microorganisms. They are enlisted as:

  1. Bacteria

    1. It is a single-celled organism.

    2. They can be spiral, rod-shaped, spherical-shaped, comma-shaped.

    3. It causes diseases like cholera and tuberculosis.

  2. Fungi

    1. Fungi are mostly multicellular organisms that cause several diseases.

    2. The moulds formed on bread are a type of fungi.

  3. Protozoa

    1. Protozoa can either be unicellular or multicellular.

    2. Amoeba and Plasmodium are examples of protozoa.

    3. They are harmful to humans as well as other organisms.

  4. Virus

    1. Viruses are disease-causing microorganisms that can only divide inside a host organism/cell. 

    2. It can affect plants as well as animals or humans. 

    3. HIV virus in humans and TMV virus in plants are examples of viruses.

  5. Algae

    1. They are the only microorganisms that are multicellular and have photosynthetic pigments.

    2. They are also known as precursors of plants.

    3. Spirogyra and Chlamydomonas are some examples of algae.


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

Ans: The microorganisms that can fix atmospheric nitrogen in the soil are bacteria. Rhizobium is one such bacteria. They help in making it to nitrogenous compounds that can be taken up by the plants.


These nitrogenous compounds are then used by the plants to make proteins and other important compounds. Rhizobacteria and Blue-green algae are examples of bacteria that have the capacity to fix nitrogen. 


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

Ans: Usefulness of microorganisms:

  1. Microorganisms such as rhizobium bacteria are used to increase soil fertility by fixing atmospheric nitrogen.

  2. They are also useful in preparing many medicines and antibiotics.

  3. Yeast is a microorganism that is used at home to make batter for fermented food. 

  4. Various fungi are the ones responsible for decaying the waste in nature, they obtain nutrients from the dead and decompose the waste.

  5. They are used in making wine, bread, pickles, and other food products.

  6. Lactobacillus bacteria are mainly used at homes to make curd from milk.

  7. Certain microbes are also used in the biological treatment of sewage and industrial effluent.

  8. Some microorganisms are taken as probiotics which provide health benefits.

  9. Bacteria are also involved in making cheese.

  10.  Acetobacter acetic is used for producing acetic acid from alcohol.


8. Write a short paragraph on the harms caused by microorganisms.

Ans: The harms caused by microorganisms are enlisted below:

  1. They can cause diseases in humans. Some diseases caused by bacteria are tuberculosis, cholera, typhoid, etc.

  2. There are viruses that can affect the cattle by causing foot and mouth disease.

  3. Microorganisms tend to reduce the productivity of the plants like wheat, rice, apple, sugarcane, etc.

  4. When microorganisms are present in our body, they can harm the body cells by producing harmful substances.

  5. There are microbes that can spoil food as well as other materials.


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

Ans: Antibiotics are the drugs or medicines that are taken to kill disease-causing microorganisms. They are produced from microorganisms. There are different types of antibiotics that are used to protect against each type of microorganisms like bacteria, fungus, and other organisms and kill them. Some examples of antibiotics are Penicillin, Tetracycline, Streptomycin, and so on.

The precautions to be taken while taking antibiotics are listed below:

  1. They should be taken under the supervision of a qualified doctor.

  2. The prescribed course of antibiotics should be taken completely for good results.

  3. Taking the correct dosage of antibiotics is important. Any dose higher than or less than the prescribed dosage can harm the body.


Benefits of NCERT Solutions Class 8 Science Chapter 2

Vedantu has been able to supply students with a Class 8 Science Chapter 2 Solution because of our amazing professors. There are several advantages to utilising this method. Some of these advantages are listed below.


  • Highly accurate solutions that have been prepared by a team of subject specialists.

  • CBSE guidelines have been strictly followed to answer all the questions.

  • Students can easily view the answer plus the detailed descriptions of every question.

  • The solutions are available in a PDF file that can be downloaded on any device for free.

  • Following the solutions and guidelines would allow the students to get maximum marks.

These benefits will ensure that students are able to grow and become better learners.


Preparation Tips for Class 8 Science

Mentioned below are some of the preparation tips which can help students to perform better in the upcoming examination.

  • Always practise as many questions as possible. Science is a subject that requires a lot of practice, and solving questions is one of the best ways to do it.

  • Make sure to solve the examples. Students often overlook the solved and unsolved examples of the chapter but solving them ensures a better understanding of the concept.

  • Make sure to use flowcharts and diagrams for understanding the concept.

  • Revise the previously learnt concept at regular intervals.

  • Always solve previous year's questions before the examination to get an idea of the format and weightage of the questions.

  • Make a note of the key formula and phrases. This would greatly help in last-minute revision.


Chapter-wise NCERT Solutions for Class 8 Science


This was the complete discussion on Microorganisms: Friend and Foe NCERT Solutions of Class 8 Science. We have learnt some of the key points and the important topics covered in the chapter along with the benefits of practising the NCERT Solutions. We highly recommend students download the NCERT solutions pdf and practise each and every question of the pdf. Solving these questions will definitely help students develop a better understanding of the concept, thus helping them perform better in the upcoming examinations. 


Conclusion

NCERT Solutions for Class 8 Science Chapter 2 - "Microorganisms: Friend And Foe" provide a comprehensive understanding of the diverse roles microorganisms play in our lives. These solutions elucidate how some microorganisms act as friends, contributing to vital processes like nutrient recycling, medicine production, and food fermentation. Simultaneously, they highlight the potential dangers posed by certain microorganisms as foes, causing diseases and contaminating food and water. By grasping the significance of maintaining a balanced relationship with microorganisms, students gain essential knowledge about hygiene, sanitation, and the responsible use of antibiotics. NCERT Solutions play a crucial role in fostering scientific temper and creating a foundation for informed decision-making in daily life.

FAQs on NCERT Solutions for Class 8 Science Chapter 2 - Microorganisms: Friend And Foe

1. What does Class 8 Science Chapter 2 deal with?

NCERT Grade 8 Science Chapter 2, Microorganisms deals with various types of microbes (harmful and useful) and their importance in various areas. Where do Microorganisms Live? Some of the main topics covered under this chapter are Microorganisms and Us, Harmful Microorganisms, Food Preservation, Nitrogen Fixation and Nitrogen cycle. It also tells us about the life cycle of microorganisms, their habitat, how they contribute in different industries and also their adversities.

2. How many topics/ subtopics are there in Chapter 2 Microorganisms?

A total of seven topics/ subtopics are there in Chapter 2 Microorganisms. Take a look below.

  • Ex 2.1 - Microorganisms

  • Ex 2.2 - Where do Microorganisms Live?

  • Ex 2.3 - Microorganisms and Us

  • Ex 2.4 - Harmful Microorganisms

  • Ex 2.5 - Food Preservation

  • Ex 2.6 - Nitrogen Fixation

  • Ex 2.7 - Nitrogen Cycle.

3. How many questions are contained in the Class 8 Science Chapter 2 exercise of NCERT book?

Nine questions are present in the Class 8 Science Chapter 2 exercise of the NCERT book and the NCERT Solutions by Vedantu contains solutions to all these nine questions in a comprehensive manner.

4. Why should I opt for the NCERT Solutions for Class 8 Science offered by Vedantu?

Vedantu’s NCERT Solutions for Class 8 Science are created by the best experts in town who have years of valuable experience in the similar field. Hence these solutions are of the best quality and provide accurate solutions to all the problems. These solutions are drafted in a lucid manner so that anyone can understand these very easily. Not only that but you will also learn how to write answers to various patterns of questions in an apt manner.

5. What are the harmful effects of microorganisms

Microorganisms are beneficial to humans in all aspects of life. They play an important role in even preparing the curd we consume daily. However, these microorganisms do come with their fair share of harmful effects. They can be pathogenic and cause diseases in humans, as is illustrated in Chapter 2 of NCERT Class 8 Science - Microorganisms: Friend and Foe. To learn more, visit the page NCERT Solutions Class 8 Science Chapter 2. 

6. Why should I refer to the NCERT Solutions for Class 8 Science Chapter 2?

Vedantu provides a wealth of educational tools to help students prepare for exams. Each NCERT chapter includes chapter exercises, which are provided at the end of the chapter. Answering the questions in these exercises allows students to not only review the chapter again, but also to comprehend the pattern of the questions posed. This is why you should visit the page Class 8 NCERT Science Chapter 2 Solutions on the Vedantu website or download the Vedantu app, where you can get these solutions for free.

7. What are microorganisms

A microorganism is a term used to refer to any living organism that cannot be viewed with the naked eye and is only visible under a microscope. Microorganisms include monera consisting of various bacteria, Protista like Euglena, and certain fungi like yeast. Microorganisms are present all around us. They even inhabit deep springs and hydrothermal vents. The human body is also home to millions of such microorganisms. 

8. What are antibiotics as mentioned in Class 8 Science Chapter 2?

In Chapter 2 of Class 8 NCERT Science, antibiotics are defined as drugs obtained from microorganisms that inhibit the growth of other microorganisms, ultimately leading to their death. Penicillin, Streptomycin, and Tetracycline are some common antibiotics that are prescribed frequently. For more information, visit the page NCERT Solutions Class 8 Science Chapter 2. However, students must note that antibiotics should never be self-administered. They should always be prescribed by a qualified doctor first.