Have you ever noticed greenish slippery patches on concrete pathways after a rainfall? Or greyish black patches on old slices of bread? Both of these are examples of microorganisms or minute living organisms in our everyday environment, which can only be seen using an instrument called a microscope. In this chapter, we will understand microorganisms and their importance for human beings. We will also learn how to distinguish good microorganisms from harmful ones.
Topics covered in NCERT Solutions Chapter 2 - Microorganisms: Friend And Foe
Types of microorganisms:
How to prevent the growth of microbes in food
Where are microorganisms found
Uses of microorganisms to humans
Diseases caused by microorganisms in
Microorganisms are the smallest known living organisms on earth. They are so small that they cannot be seen with the naked eye. They are also known as microbes. Microbes may be unicellular or multicellular. They form colonies or grow in clusters. They can be seen in patchy or mouldy designs, which are colonies of millions of microorganisms. Microbes can move from one place to another using their flagella, a tail-like propeller that helps them move forward. They swim by moving all parts of their body. They reproduce by cellular division. Some microorganisms, such as green algae, can make their food, but most of them are parasites.
Some microbes, such as viruses, can survive in dormant states till they find a host to multiply.
For example, the blackish-grey substance on bread is a fungus, and the greenish patch on concrete is algae. These organisms can be seen and studied with the help of a magnifying lens in a microscope.