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

The NCERT Class 8 Science, Chapter 2 deals with Microorganisms: Friend and Foe. In this chapter, you will learn about the different microorganisms present around us. You will learn more about these tiny creatures that cannot be seen by a naked eye. These organisms are called microorganisms or microbes.

In this chapter, you will learn about the advantages and disadvantages of these microorganisms. These microbes have few benefits like medicinal use, soil fertility and other commercial purposes. In this chapter, you will learn about both the uses and dangers of these microorganisms. You will also learn techniques to preserve food items from getting spoilt due to these microorganisms.

To know more about NCERT Solutions for Class 8, Science Chapter 2, Microorganisms: Friend And Foe, let’s look at the topics and sub-topics of this chapter:

2.1 Microorganisms

2.2 Where do Microorganisms live?

2.3 Microorganisms and Us

2.4 Harmful Microorganisms

2.5 Food Preservation

2.6 Nitrogen Fixation

2.7 Nitrogen Cycle

In Class 8 Science Chapter 2, you will learn-

Section 2.1 – This section deals with Microorganisms. In this section, you will learn more about microorganisms, their different types and characteristics. You will also learn about how these microorganisms spread in the atmosphere. This section gives a brief overview of microorganisms and their types.

Section 2.2 – This section deals with the concept where do microorganisms live. In this section, you will learn that microorganisms could be unicellular or multicellular. These microorganisms live in all types of environment. In this section, you will learn how these microorganisms survive in different environments and some depend on hosts for survival.

Section 2.3 – This section deals with the link between microorganisms and human beings. In this section, you will learn about the coexistence of the two creatures and their inter-connection with each other. This section helps you to understand that while some of these microorganisms are beneficial to us and others can be harmful and disease-causing. In this section, you will learn about friendly microorganisms, making of curd and bread, commercial use and medicinal use of these microorganisms. You will also learn that these microbes are used in certain vaccines and also to increase soil fertility.

NCERT Class 8 Science, Chapter 2 helps you to understand the concept of Microorganisms. In this chapter, you will learn the benefits of microorganisms and also understand the harm they can cause to human beings. This chapter helps to understand the coexistence of microorganisms and human beings. In this chapter, you will learn how these microorganisms are useful – in medicines, vaccines, soil fertility, cleaning the environment and for preparation of curd and bread. You will also learn how these microorganisms cause diseases in plants and animals, and the different methods to prevent food from getting spoilt due to these microorganisms.

Section 2.4 – This section deals with harmful microorganisms. In this section, you will learn about disease-causing microbes called pathogens. You will learn how these microorganisms cause diseases in human beings, plants and animals. There are insects and animals that act as carriers of disease-causing microbes. In this section, you will understand that the spreading of such disease-causing microbes can cause various communicable diseases, which may even be fatal. You will also learn about food poisoning, which is caused by microorganisms entering the food items.

Section 2.5 – This section deals with food preservation. In this section, you will learn to prevent food from getting spoilt due to microorganisms. You will learn that the food gets spoilt due to microbes entering the food and causing the deterioration. In this section, you will learn various techniques of preventing food items such as chemical method by using preservatives, using common salt, storage and packaging, sugar, oil and vinegar, and hot & cold treatment known as pasteurisation.

Section 2.6 – This section deals with nitrogen fixation. In this section, you will learn more about rhizobium, which is involved in nitrogen fixation in the soil. Certain bacteria and blue-green algae present in the soil, fix nitrogen and convert it into compounds of nitrogen. It is further used by plants through their roots.

Section 2.7 – This section deals with the nitrogen cycle. Nitrogen is one of the essential constituents of all living organisms. You will learn that the atmospheric nitrogen cannot be directly taken by the plants and animals. In this section, you will learn about the cycle present in the environment which produces nitrogen from the dead plants and animals with the help of microbes. Then this nitrogen is used by plants through soil, and animals when they consume these plants in the form of nutrients. You will learn that through this nitrogen cycle, the level of nitrogen remains stable in the atmosphere.

To know more about the NCERT solutions Class 8 Science, Chapter 2 – Microorganisms: Friend and Foe explore the Exercises and questions below: