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

JEE Mains & Advanced

NCERT solutions for class 8 science chapter 2 Microorganisms: Friend and Foe help students to solve exercise questions. NCERT solutions will help students to solve all the exercise questions in detail. NCERT solutions include various types of questions like fill in the blank, match the following questions with true or false, and descriptive type questions from chapter 2.

By studying this chapter, students will learn about microorganisms and their habitats. They will also learn about classes of microorganisms such as bacteria, fungi and protozoans, as well as viruses. They will learn about the mode of reproduction of microorganisms, how they are used, and how they are harmful. They will also know about soil microorganisms and how they fix nitrogen by bacteria. By studying this chapter, they will be able to solve all their doubts in class 8 science in a simple and interesting way.

NCERT Solutions for Class 8 Science Chapter 2 Topics

Section Name

Topic Name


Microorganisms: Friend and Foe




Where do Microorganisms Live?


Microorganisms and Us


Harmful Microorganisms


Food Preservation


Nitrogen Fixation


Nitrogen Cycle

2.1 Microorganisms: Microorganisms are tiny living things that you can't see with your own eyes. They come in all shapes and sizes, from bacteria to viruses to fungi to archaea to protists. Even though they're so small, they're really important for a lot of different things, like the environment, industry, and medicine.

2.2 Where do Microorganisms Live?: Microorganisms can range from single-celled bacteria, algae, and protozoa to multi-celled organisms like algae and fungi. They can live in any kind of environment, from cold climates to hot springs, deserts to marshy lands, and even inside the bodies of animals and humans. Some microorganisms can grow on other organisms, while others can live independently.

2.3 Microorganisms and Us: Microorganisms play an important role in our lives, both positively and negatively.

Following points will be discussed in the section 2.3 Microorganisms and Us:

  • Friendly Microorganisms

  • Making of Curd and Bread

  • Commercial use of microorganisms

  • Medicinal use of microorganism

  • Increasing soil fertility

  • Cleaning the environment

2.4 Harmful Microorganisms: Pathogens are harmful microorganisms that cause diseases and health problems in humans, pets, and plants. Pathogens have the capacity to enter and multiply inside their host, causing symptoms and health problems.

Following points will be discussed in the section 2.4 Harmful Microorganisms: 

  • Disease causing microorganisms in humans

  • Disease causing microorganisms in animals

  • Disease causing microorganisms in plants

  • Food Poisoning

2.5 Food Preservation: Food preservation is a term used to describe the process of preserving food by preventing or slowing down the growth of harmful organisms, enzymes and other substances that can cause food spoilage. The purpose of food preservation is to extend the life of food.

Following points will be discussed in the section 2.5 Food Preservation: 

  • Chemical Method

  • Preservation by common salt

  • Preservation by sugar

  • Preservation by oil and vinegar

  • Heat and cold treatments

  • Storage and Packing

2.6 Nitrogen Fixation: Nitrogen fixation is the biological process by which atmospheric N2 is transformed into ammonium nitrate (NH3), or other nitrogen-containing compounds that plants and other organisms can use. Although atmospheric nitrogen is abundant (accounting for about 78% of the Earth’s atmosphere), most plants and animals can’t use it as gaseous nitrogen. The process of nitrogen fixation is necessary for making nitrogen accessible in forms that are incorporated into the molecules needed for life, like proteins and DNA.

2.7 Nitrogen Cycle: The nitrogen cycle is an essential biological process that describes the movement of nitrogen through various forms and compartments in the atmosphere. Nitrogen is a fundamental component of all living organisms, forming the building blocks of proteins, DNA and RNA, and other essential molecules.

Key Features of Class 8 Science Chapter 2

  • Microorganisms are microscopic organisms that are not visible to the naked eye. They can inhabit a variety of environments, such as cold climates, hot springs, deserts, and marshy lands, and can be found in the air, water, and animal and plant bodies. 

  • These organisms may be single-celled or multi-celled. Bacteria, fungi, protozoa, and some algae are among the most common microbes, though viruses are also considered microbes. 

  • Viruses are distinct from other microorganisms in that they reproduce only within the host organism, such as bacteria, plant, or animal cells. 

  • Additionally, some microorganisms are used in the commercial production of medicinal products and alcohol.

  • Microorganisms break down organic waste and dead plants/animals into simple substances and purify the environment

  • Protozoans cause diseases such as dysentery, malaria, etc.

  • Microorganisms grow on food and cause food poisoning.

  • Microorganisms live in leguminous plant root nodules and can fix nitrogen from air to soil and increase soil fertility

  • Bacteria present in soil fix nitrogen from air and convert it into nitrogenous compounds

  • Some bacteria convert nitrogen compounds present in soil to nitrogen gas which is released into the atmosphere.

Benefits of Downloading the PDF of NCERT Solutions Class 8 Science Chapter 2 Microorganisms Friend and Foe 

Downloading NCERT Solutions for class 8 Science Chapter 2 “Microorganisms: friend and foe” PDF from a popular online learning platform like eSaral can provide several advantages over traditional sources. eSaral often offers more advanced features and resources to help students in their learning. Here are some of the advantages that eSaral’s NCERT Solutions can offer:

  • eSaral’s solutions may include step by step explanations to help students gain a thorough understanding of the solution process.

  • eSaral could provide additional practice questions beyond NCERT textbook exercises to give students more opportunities to strengthen their understanding

  • Instant access: Digital resources such as eSaral solutions provide students with instant access to the information they need. Students can easily find what they need whenever they need it.

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Frequently Asked Questions

Question 1: What are microorganisms?

Answer 1: Microorganisms, commonly abbreviated to microbes, are microscopic living entities that are not visible to the naked eye. Microorganisms include bacteria, viral and fungal organisms, as well as archaea and protists.

Question 2: How do microorganisms affect our lives?

Answer 2: Microorganisms play a variety of roles in our lives, from food production and digestion to medicine, the balance of the environment, and more. Some of these organisms can also cause diseases.


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