this presentation will tell you about the mico-organisms how can they be friendly and how can they harm us. please hit a like if you liked it.

1. CH-2 MICROORGANISMS : FRIEND AND
FOE
TODAY WE WILL LEARN ABOUT :-
.MICROORGANISMS
.TYPES OF MICROORGANISMS
.WHERE DO MICROORGANISMS LIVE
.MICROORGANISMS AND US
. FRIENDLY MICROORGANISMS
. MAKING OF CURD AND BREAD
. COMMERCIAL USE OF MICROORGANISMS
.MEDICINAL USE OF MICROORGANISMS
.VACCINE
.INCREASING SOIL FERTILITY
.CLEANING THE ENVIRONMENT

2. . Several organisms that we can not see from our naked eyes
are called microorganisms.
. Microorganisms are only visible under microscope.
. These can be harmful or useful in some or other way.

3. Types of microorganisms
Bacteria Fungi Protozoa algae
FACT FILE:-
Viruses are also microscopic. They, however, reproduce only inside the cells of the host
organisms ,which may be a bacterium, plant or animal. Most cough are caused by viruses.
And also those serious diseases like polio , chicken pox etc.

4. . bacteria (singular bacterium) are a type of biological cell.
. Bacteria, also called germs, are microscopic organisms not visible with the naked eye.
Bacteria are everywhere, both inside and outside of your body.
. Typhoid and tuberculosis (tb) are bacterial diseases.

5. . Fungi can be single celled or very complex multicellular organisms.
. A group called the decomposers grow in the soil or on dead plant matter where they play an
important role in the cycling of carbon and other elements.
.

6. . Protozoa is an informal term for a group of single-celled free-living organimsm, that feeds
on organic matter such as other microorganisms .
. Diseases like dysentery and malaria are caused by protozoa.

7. . Algae is an informal term for a large and diverse group of organisms.
. Algae are usually green, but they can be found in a variety of different colours.

8. WHERE DO MICROORGANISMS LIVE ?
. Bacteria can live in a variety of environments, from hot water to ice.
. Fungi grow in a wide variety of environments around the globe. Most fungi are terrestrial and are found in
all temperate and tropical areas
. protozoa live in a wide variety of moist habitats including fresh water, marine environments and the soil.
. Algae exist in environments ranging from oceans, rivers, and lakes to ponds, brackish waters and even
snow
FACT FILE:-
. Microorganisms like amoeba can live alone, while fungi and bacteria may live in
colonies.

9. MICROORGANISMS AND US
Initially it was thought that all the micro-organisms are harmful and cause diseases. Later on scientists
discovered that only a handful of micro-organisms are harmful and cause diseases. Most of the
microorganisms are harmless and some of the micro-organisms are even beneficial to us (or useful to us).
Micro-organisms play an important role in our lives. We will now describe the beneficial effects of micro-
organisms in detail.

10. Friendly microorganisms
. Microorganisms are used for various purposes.
. They are used in the preparation of curd, bread and cake.
. They are also used in cleaning up of the environment.
. For example, the organic wastes (vegetable peels, remains of animals, faeces, etc.) are broken down into
harmless and usable substances by bacteria.
. Recall that bacteria are also used in the preparation of medicines.
. In agriculture they are used to increase soil fertility by fixing nitrogen.
FACT FILE:-
Microorganisms have been used for the production of alcohol since ages.

11. I saw that my mother
added a little curd in
warm milk to set the
curd for next day. I
wonder why?

12. MAKING OF CURD
Milk is turned into curd by bacteria called lactobacillus. In order to make curd, a little pre-made curd is
added to warm milk and set aside for some time. Curd contains several micro-organisms including
Lactobacillus bacterium (Plural of Lactobacillus is Lactobacilli). Lactobacilli bacteria promote the
formation of curd from milk. When a little of pre-made curd is added to warm milk, then Lactobacilli
bacteria present in curd multiply in milk and convert it into curd.

13. MAKING OF BREAD
Yeast is used in the baking industry for making bread. When yeast is mixed in dough
for making bread, the yeast reproduces rapidly and gives out carbon dioxide gas during respiration.
The bubbles of carbon dioxide gas fill the dough and increase its volume. This makes the bread
‘rise’.
The holes in the bread are due to the bubbles of carbon dioxide given off during the baking process.
This makes the bread light, soft and spongy.

15. WHAT IS FERMENTATION?
This is smell of alcohol as sugar has been converted into yeast .this process of conversion of sugar
Into alcohol is known as fermentation.
FACT FILE:-
Louis Pasteur discovered fermentation in 1857

16. MEDICINAL USE OF
MICROORGANISMS
. Making antibiotics
. Making vaccine
. Making food supplements: Microbes like Chlorella (a type of algae) are rich in proteins and other
nutrients and are used as food supplements.
. In human body: Bacteria like Lactobacillus acidophilus live in human intestines, where they help
to digest food and destroy disease-causing microbes.

17. In 1929, Alexander Fleming was working on a culture of disease-causing bacteria.
Suddenly he found the spores of a little green mould in one of his culture plates. He
observed that the presence of mould prevented the growth of bacteria. In fact, it also
killed many of these bacteria. From this the mould penicillin was prepared
Fact! Fact! Fact!

18. ANTIBIOTICS
. A medicine which stops the growth of , or kills the disease causing microorganisms is
called an antibiotic ……….that is why the doctor prescribes you a antibiotic when you
Fall ill
. these days, a large number of antibiotics are being produce from microorganisms
Such as fungi.
. Examples of antibiotics are:- penicillin, streptomycein , erythromycein and tetracycline.
. Antibiotics are used to treat many disease in humans .
. Antibiotics are however, not effective against disease caused by virus.
FACT FILE:-
Alexander Fleming found the first antibiotic called penicillin.
Penicillin is made from fungus.

19. VACCINE
. A vaccine is a special kind of preparation (or medicine) which provides immunity (or protection)
against a particular disease.
. These days vaccine are made up on the large scale from microorganisms to protect human
beings and other animals from several disease .
FACT FILE:-
Edward Jenner discovered the vaccine for small pox in 1798

20. INCREASING SOIL FERTILITY
Some bacteria and blue green algae are able to fix nitrogen from the atmosphere to enrich
soil with nitrogen and increase its fertility. These microbes are commonly called biological nitrogen
fixers.

21. CLEANING THE ENVIRONMENT
How to Clean:
Decomposing harmful and smelly dead
remains of plants and animal wastes (like
faeces, dung, urine, etc.) into harmless
materials by micro organisms.
Benefit:
These micro-organisms helps in
recycling the nutrients (present in dead
plants, dead animals and animal wastes)
in nature which can then be used as food
by green plants.

22. HARMFUL MICROORGANISMS
• Microorganisms are harmful in many ways. Some of the
microorganisms cause diseases in human beings, plants and
animals. Such disease-causing microorganisms are called
pathogens. Some microorganisms spoil food, clothing and leather.
Let us study more about their harmful activities.

23. DISEASE CAUSING MICROORGANISMS IN
HUMANS
• Pathogens enter our body through the air we breathe, the water we
drink or the food we eat. They can also get transmitted by direct
contact with an infected person or carried by an animal. Microbial
diseases that can spread from an infected person to a healthy person
through air, water, food or physical contact are called communicable
diseases. Examples of such diseases include cholera, common cold,
chicken pox and tuberculosis.
• When a person suffering from common cold sneezes, fine droplets of
moisture carrying thousands of viruses are spread in the air. The
virus may enter the body of a healthy person while breathing and
cause infection.

24. Then how do you prevent
the spread of
communicable disease
We should keep a hanker
cheif on the nose and
mouth while sneezing. It
is better to keep a
distance from infected
person

25. Thank you