3. contents
• What is micro-organisms
• Types of micro-organisms
• Friendly micro-organisms
• Harmful micro-organisms
• Disease causing by micro-organisms in
humans and in plants
• Food preservation
4. Micro-organisms
• Micro-organisms are very small organisms that
can not be seen with naked eye , but can be
seen with the help of microscope .
• Micro-organisms may be unicellular or
multicellular .
• Micro-organisms may live alone or
communities .
• Micro-organisms are found in all kinds of
environment like ice cold climate , hot spring ,
5. Types of Micro-organisms
• There are different types of micro-organisms like
bacteria , fungi , algae , protozoans etc.
• Viruses are considered as to be micro-organisms
they are different from other organisms because they
produce only in the body of host cells examples of
host cell is worms , nematodes etc.
6. Friendly Micro-organisms
• Micro-organisms are used for making bread , curd
from milk , cheese pickles , cakes , alcohols etc.
• Micro-organisms are used for making medicines .
• Micro-organisms helps in fixing atmospheric
nitrogen
7. • Making Curd from milk : The bacterium called
lactobacillus reproduces in milk which convert milk
into curd .
• Making bread ; the fungus called yeast produces in
flour dough and produces carbon dioxide during
respiration which makes the dough soft and helps in
making cakes , biscuits , bread etc.
• making medicines ; some bacteria and fungus are4
used to make medicines which kills or stops the
growth of disease causing micro-organisms such
medicines are called as antibiotics
8. • Examples ; streptomycin , tetracycline ,
erythromycin .
• Vaccines are important to protect us from
disease and vaccines protect us from different
diseases like polio , cholera , typhoid etc.
9. Harmful Micro-organisms
• Some microorganisms cause diseases in plants and
animals. Such disease causing microorganisms are
called pathogens .
• Some microorganisms grow in food substances and
produce toxic substances and makes the food
poisonous. Food poisoning causes illness and even
death.
10. Disease causing Microorganisms in
Humans
• Disease causing micro-organisms enter our body
through air , water , food these micro-organisms
are called as pathogens .
• Disease which can spread from an infected person
to a healthy person are called communicable
diseases .
• E.g. :- chicken pox , flu , Tb etc. .
11. • Some insects and animals act as carriers of disease
causing microbes.
• E.g. :- House fly, Female anopheles mosquito
(malaria), Female aedes mosquito (dengue fever) etc.
13. Disease causing microorganism in plants
• Micro-organisms like rice wheat causes diseases in plants
like rice , wheat , potato , sugarcane , apple etc these
produces crop yield these diseases controlled by using
chemicals which kill microbes .
14. Food preservation
• Food is spoilt by microorganisms. Spoilt food has
bad smell and bad taste and causes food poisoning.
Food can be preserved by protecting it from
microorganisms. Food can be preserved by different
methods.
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