Micro organisms

Micro organisms

Micro organisms –

If some curd is added to milk then the whole milk gradually turns into curd.

Similarly, fruits, vegetables etc. kept for a long time rot.

Sometimes we become ill suddenly. Let us try to know why this happens and what is the reason for it?

You know that various types of creatures like trees, plants, elephants, humans, birds, fish, ants, etc. live on our earth.

All these are visible to us with our eyes, they

We call large organisms (Macro Organism).

But these are not the only creatures in the living world.

There is a world of living beings which we cannot see with our eyes but from time to time we feel their presence.

To see such organisms, a microscope is required, hence we call them microorganisms.

These micro organisms are also the cause of curd formation from milk, rotting of substances and some diseases occurring in living beings.

Come on let us see how small they are –

Just as in the animal world, there is a lot of variation in the shape and size of large creatures (a giant elephant and a small ant).

Similarly, there is a lot of variation in the shape and size of microorganisms.

An amoeba is approximately three million times larger in size than an ordinary bacteria.

Some microorganisms can be seen through a simple microscope like amoeba, paramecium etc.

Apart from these, some microorganisms like algae, fungi etc.

When they are in a group, we can see them with our eyes

but to see one of them (one organism) we need a microscope,

there are some microorganisms which are not visible even with a normal microscope.

These can be seen only with a very powerful electron microscope like bacteria, viruses etc.

Microorganisms are very small in size, hence to measure their length and width,

only micro units have to be used, because units like centimeter, millimeter are too big to measure them.

Come, let us try to understand this –

Draw a 1 mm long line segment on your copy using the scale you use for measurement.

Now if you can divide it into 1000 equal parts, then each part will be equal to one micrometer,

that is, there are 1000 micrometers in one mm.

Objects smaller than about 100 micrometers are not visible to us.

The size of Paramecium is about 100 micrometers,

some organisms are even smaller than Paramecium,

they are measured in nanometers.

If 1 micrometer is divided into 1000 equal parts,

each part will be equal to 1 nanometer.

The diameter of the spherical polio virus is 28 nanometers.

Now you must have understood how small microorganisms are.

Where do we find micro-organisms?

You will be surprised to know that microorganisms are found everywhere on Earth.

This means that they are present in air, water, soil, on and inside the bodies of animals.

Found on Earth from very hot to very cold places, these microorganisms can survive in any conditions.

How many types of micro- organisms –

You noticed that you can see different types of microorganisms in just one drop of water.

Some of these are unicellular and some are multicellular.

There are mainly five types of microorganisms –

1- Algae

2- Fungi

3- Protozoa

4- Bacteria



Algae are found only in water or in moist places.

You may also have seen a green or brown layer accumulated in wet, moist places,

in ponds or stagnant water of rivers, these are actually algae.

Which we also call moss.

Algae are usually green, red or brown .

Their special color is due to a special pigment.

Algae , micro organisms

Write in your notebook the name of the pigments found in green algae and the process they perform to make food.


You must have seen fungus which often appears in the form of yellow, brown,

black, gray spots on pickles, jams, fruits, vegetables,

wet clothes, old shoes, walls, wood etc.

These are actually different types of fungi.

Fungi, micro organisms


You have read about Amoeba, Paramecium, Euglena.

These are all easily found unicellular protozoa.

Organisms of this group are found everywhere like other microorganisms in water, plants and animals’ bodies and soil.

Some protozoa have one or more thread-like structures.

With the help of which they move in water.

You know that malaria is caused by the bite of the female Anopheles mosquito,

but you will be surprised to know that these mosquitoes are carriers of the malaria pathogen –

a protozoa called Plasmodium and can spread these germs from a sick person to a healthy person.

Do the work of delivery.

Some other protozoa also cause diseases in humans and animals like Entamoeba and Giardia etc.

A common disease caused by these is dysentery.


These are found around us and everywhere else.

These were first seen in 1675 AD by a scientist named Antonivon Leeuwenhoek with the help of a microscope made by himself.

Bacteria are generally spherical, rod-shaped and spiral-shaped.



This is the most microscopic creature.

Compared to other micro organisms, viruses are so small that they can be seen only with the help of electron microscope.

They can grow only in the body of other host organisms.

Their presence can be detected by the effect they have on the host organisms.

Viruses that live in plants are called plant viruses,

viruses found in animals are called animal viruses and viruses found in bacteria are called bacteriophages.

Bacteriophage virus has been found in Ganga water.

It is also not certain whether they should be called living or nonliving.

Because outside the host cell they are like non-living particles.

Therefore, some scientists also consider them as the link between living and non-living.


Some diseases like cold, fever, flu, eye disease (conjunctivitis)

which we also call ‘conjunctivitis’, etc. spread very fast.

Apart from these, rabies, polio, measles, AIDS etc. are also viral diseases occurring in humans.

Viruses also cause many diseases in other animals and plants.

You learned about HIV through newspapers, television and radio.

/ Must know about AIDS. AIDS in humans is terrible and fatal.

There is no cure for it but it can be avoided by adopting preventive measures.

That is why all communication media are alerting people.

We see the virus in microscope.

Learn more –

Human papillomavirus disease

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Aids meaning , symptoms, prevention

Malaria is caused by

Typhoid causes and prevention

Diarrhoea Symptoms and prevention

Tuberculosis is caused by

Influenza virus , causes and controle

Jaundice in hindi

Scurvy disease , symptoms and prevention

Cholera is caused by

Rabies symptoms and prevention

Beri beri symptoms and prevention

Filaria caused by , symptoms and prevention

Author: educationallof

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