Short Notes and Formulas of class 8 science chapter-Microorganisms

Short Notes and Formulas of class 8 science chapter-Microorganisms

May 13, 2022, 16:45 IST

Class- 8 science chapter-Microorganisms

We cannot see them, we cannot hear them but they are with us: There are about 100 trillion microorganisms in and around our bodies. The fact is that without microorganisms we would not survive. A microorganism is a living organism that is so small that it can only be seen with the aid of microscope. Fungus that grows on the bread can be seen with a magnifying glass. Bacterial cells are about one hundredth of the size of a human cell and viruses are much smaller.

While it is true that microorganisms are responsible for a large number of human diseases, they also make it possible the cycle of chemical exchange between organisms and their environment. The decision as to whether bacteria are friend or foe becomes more difficult when both the positive and negative aspects of the relationship between human beings and microorganisms is considered. However, it can be concluded that bacteria can survive without us but we would not be able to live without them.

The study of microorganisms is known as microbiology.

Major Groups of Microorganisms

• Bacteria - Eg. Lactobacillus and Rhizobium
• Fungi – Eg. Penicillium and Aspergillus
• Protozoa - Eg. Amoeba and Paramoeciu

Where do Micro-organisms live?

• They are found in all living beings, plants and animals. Microorganisms can live in the air, on land, and in fresh or salt water environments. However, most microbes need water to survive, therefore, wherever there is water there are microbes.
• There is not one place on earth that does not have bacteria or some other microorganism living there.
• They can survive at temperatures less than 20°c temperatures, hotter than boiling water

Microorganisms and us

• Lactobacillus for the production of curd (yogurt) from milk.
• E.coli bacteria are used for the production of drugs such as insulin and antibiotics, after genetically modifying the bacteria.
• Nitrosomonas is used for sewage treatment.
• E.coli produces vitamin k and vitamin B6 and Biz in our digestive tract which is essential nutrients for our body.
• Streptomyces bacteria is used in making antibiotics.
• Fungus Penicillium revolutionized medicine with the discovery of penicillin antibiotic obtained from it.
• Microorganisms such as bacteria and fungi act as decomposers in the ecosystem, decomposing (viii)  Many vaccines are prepared from microorganisms to protect them from like tuberculosis, polio etc.
• Yeast is used in dough to make porous and spongy bread and cakes.
• Yeast is also used to convert natural sugars present in grains into alcohol. dead plants and animals. Through the decay process, elements such as carbon, nitrogen and sulphur are released into the soil, making it more fertile.

Fermentation

• Louis Pasteur discovered the process of fermentation
• The process of converting sugar into alcohol is called fermentation.
• Yeast convert the natural sugars present in grains into alcohol

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