Water and soil are full of tiny
organisms, thought not all of them fall
into the category of microbes.
Microorganisms or microbes are so
small in size that they cannot be seen
with the unaided eye. That is why
these are called microorganisms or
Microorganisms are classified into four major
groups. These groups are bacteria, fungi, protozoa
and some algae. Some of these common
Microorganisms are shown in figs. 2.1-2.4.
Bacteria are a large domain of singlecelled, prokaryote microorganisms. Typically a few
micrometres in length, bacteria have a wide range of
shapes, ranging from spheres to rods and spirals.
There are typically 40 million bacterial cells in a gram
of soil and a million bacterial cells in a milli litre of
fresh water. Bacteria are vital in recycling nutrients.
A fungus is a member of a large group of
eukaryotic organisms that includes
microorganisms such as yeasts and molds
(British English: moulds), as well as the
more familiar mushrooms. These organisms
are classified as a kingdom, Fungi, which is
separate from plants, animals, and bacteria.
Protozoa are a diverse group of single cell eukaryotic
organisms, many of which are motile. Historically protozoa
were defined as single cell protests with animal-like
behavior, e.g. movement. Protozoa were regarded as the
partner group of protests to protophyta which have plantlike behavior, e.g. photosynthesis
Algae are a large and diverse group of
simple, typically autotrophic organisms, ranging from
unicellular to multicellular forms, such as the giant
kelps that grow to 65 meters in length. They are
photosynthetic like plants, and "simple" because their
tissues are not organized into the many distinct
organs found in land plants.
Viruses are also microscopic. They,
however., reproduce only inside the cells of the host
organism. Which may be a bacterium, plant or animal.
Some of the Viruses are shown in fig.2.5. common
ailments like cold, influenza (flu) and most coughs are
caused by Viruses. Serious diseases like polio and
chicken pox are also caused by viruses.
A virus is a small infectious agent that can
replicate only inside the living cells of
organisms. Most viruses are too small to be seen
directly with a light microscope. Viruses infect
all types of organisms, from animals and plants
to bacteria and archaea.
What is microorganisms?
Name four types of microorganisms?
Give two examples of protozoa and fungi?
By which microorganisms dysentery and malaria
Name the serious diseases caused by viruses?
Where viruses reproduce ?
by which object we can see the microorganisms?
TUSHAR SOLANKI , GAYATRI VALLAPH PAL ,
ARNAV SIKKEWAL , HIMANSHU GUPTA ,
ARYAN WAGADRE ,