Question

UJU DY Microorganisms.
Louis Pasteur, Alexander Fleming and Edward Jenner, Explain with diagram.​

Answer 1

Answer:

Grade VIII:

Lesson 2. Micro-Organisms: Friend and Foe

MICROORGANISMS

Friendly Microorganisms

Living organisms that cannot be seen with

our necked eyes are known as

Micoorganisms.

Marking of Cured

and Bread Commercial Use

Disease – causing

Microorganisms in

Humans

 The bacterium, Lactobacillus

promotes the formation of curd.

It multiplies in milk and

converts it into curd.

 Yeast reproduces rapidly and

produces carbon dioxide during

respiration. Bubbles of he gas fill

the dough and increases its

volume so yeast is used in the

banking industry for making

breads, pastries and cakes.

 Used for the large scale

production of alcohol,

wine and acetic acid

(vinegar).

 Yeast is used for

commercial production of

alcohol and wine.

 Diseases that can be spread

from an infected person to a

healthy person are called

communicable diseases.

 They are caused by pathogens

that can enter the body

through the air we breathe,

water we drink and food we

eat.

Anthrax: it is a fatal disease of

humans and cattle caused by a

bacterium

Food and Mouth Diseases : it is a

diseases that affects cattle and is

caused by a virus.

Citrus Canker: Caused by bacteria

and is spread by air

Rust of Wheat: Caused by fungi

and spreads through air and

seeds.

Yellow Vein Mosaic of Okra

(bhindi) : Caused by virus and

spread by insects.

Foods are spoilt by

microorganisms when they get

favourable conditions of air,

warmth and moisture. Increases

in number and produce toxic

substances that are harmful and

poisonous.

Harmful Microorganisms

Some of the microorganisms causes diseases in

human beings, plants and animals. Such disease

causing microorganisms are called pathogens.

Medicinal Use

 Medicines kill or stop the

growth of the disease – causing

microorganisms.

 Such medicines are called

antibiotics.

 Antibiotics are being produced

from bacteria and fungi.

Increasing Soil

Fertility

Preservatives like sodium

benzoate and sodium

metabisulphite are used in

jams and squashes.

Vaccine

 Vaccines are made on a large

scale from microorganism to

project humans and other animals

from .microorganism to protect

humans and other animals from

several diseases.

 Several diseases, including

cholera, tuberculosis, smallpox

and hepatitis can be prevented by

vaccination.

Cleaning of Environment

EnEnviromment  The microorganisms decomposes

dead organic waste of plants and

animals converting them into simple

substances.

 These substances are again used by

other plants and animals.

 Microorgansms can be used to

degrade the harmful and smelly

substances and thereby clean up the

environment.smelly substaunces and

thereby clean up the environment

Disease – causing

Microorganisms in

Animals

Disease – causing

Microorganisms in

Plants

Food Poisoning

Food Preservation

Chemical method By Sugar Heat and Cold Treatments

Sugar syrup containing more than 68% sugar

also stops bacterial growth as very less free

moisture is available for, it Microorganisms that

are already present in the food materials,

therefore,

 Heating is used for killing germs in milk at home.

Thus, Milk, is prevented from spoilage by

boiling.

 Milk is made germ free by pasteurization. In this

process milk is heated at 70o C for 15 seconds

and is then suddenly chilled and stored, this

prevents the growth of microbes, this process

was discovered by Louis Pasteur.

By common salt

 The presence of high concentration of salts (15%

to 18%) drains out the water from food materials

through a process called osmosis and prevents

bacterial growth which spoils the food.

 The vegetable and fruits such as tamarind, beans,

raw mango, amla, and non-vegetable items like

fish and meat are often preserved by using salt.

Bacteria and blue green algae are

able to fix nitrogen from the

atomosphere to enrich soil with

nitrogen and increase its fertility.

Oil and vinegar is used in the preparation

of pikles, chutney, ketchups and squashes.

These preservatives do not allow the

growth of microorganisms and thus, help

in preserving the food.

By Oil and Vinegar

These days dry fruits and even vegetables

are sold in airtight packets to prevent the

attack of microbes.

Storage and packing

Name of the Disease Pathogen Mode of Transmission

Tuberculosis Bacteria Air/Personal contact

Cholera Bacteria Water

Typhoid Bacteria Water

Measles Virus Air/Personal Contact

Hepatitis B Virus Water

Malaria Protozoa Mosquito

Chickenpox Virus Air/Personal contact

Polio Virus Air/Personal Contact

Answer 2

Answer:

The concept of spontaneous generation—the notion that microbes could appear out of thin air—was disproved by Louis Pasteur, who also invented the pasteurisation process and gave it his name.  

Explanation:

• He also created some of the first vaccines in history and established for the first time that infectious diseases are caused by microbes.
• Penicillin was discovered by a Scottish physician and scientist named Alexander Fleming. Fleming had extracted nasal secretions from a patient who was suffering from a head cold. To cultivate any bacteria that could have been there, he cultivated the secretions.

English surgeon Edward Jenner is credited with developing the smallpox vaccine. The structures of British medical practise and education were changing gradually when Jenner was born.

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