microorganisms friend and foe - microorganisms class 8

 Microorganisms: Friends and Foe

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 What is microorganisms?

A living organism that is very minute to be seen by the naked eye, especially a single celled organism, such as a bacterium or viruses is called microorganism.

What is microbes?

Those microorganisms which can be seen only through a powerful microscope is called microbes.

Write some characteristics of microorganisms ?

Some characteristics of microorganisms are

1- microorganisms are either one-celled organisms or multicellular organisms.

2- they can exist in extreme conditions of temperature and drought, in hot water springs or in desert and marshy lands.

3- they occur in air, water, soil , in and on the body of living organisms 

4- during unfavourable conditions, microorganisms enclose themselves in hard resistant covering called the cyst. When environmental conditions become favourable, the cyst repture and microorganisms come out and multiply themselves.

5- some microorganisms are helpful to us in agriculture and industries while some other microorganisms are harmful to us and make us sick.

6- microorganisms may be autotrophs, heterotrophs, saprophytic or parasitic.

What is microbiology?

 The study of microorganism is called microbiology.

What are  microbiologists?

 The scientists who study about microorganisms are called microbiologists.

What is the contribution of Louis Pasteur in microorganisms?

Louis Pasteur is the father of bacteriology. He discovered microorganisms in the air. He concluded that bacteria are responsible for fermentation of food. He also gave the famous germ theory of disease.

What is microscope?

A microscope is an instrument that makes tiny things look bigger. it 

magnifies objects.

 

 Who was the first known person who discover microorganisms and seen bacteria?

 Anton van Leeuwenhoke was the first known person who discover microorganisms and seen bacteria with the help of own microscope. He discovered microorganisms in rainwater.

Who is the father of bacteriology?

Louis Pasteur is the father of bacteriology. The study of bacteria is called bacteriology. Louis Pasteur was the first who seen bacteria in air.

How many types of microorganism?

 There are five types of microorganism.

1- Bacteria

2- Algae

3- Protozoa

4- Fungi

5- Viruses

What is bacteria?

Bacteria is  simplest living organism which are found all around us. They are mostly single- celled tiny organisms. they live together in colonies of millions. It is the oldest organisms on our planet.

 

Write four  properties of bacteria.

The four  properties of bacteria are

1- Bacteria are single- celled organism.

2- Bacteria are larger than viruses.

3- The size of bacteria are varies between 0.2-100 microns. (1micron =1/1000 of a millimeter).

4- Bacteria are found everywhere on the earth. They also found inside the body of living organisms.

 How many types of bacteria? Name them.

 There are four types of bacteria.

1- Rod-shaped bacteria- It is also called bacilli.

2- Spherical-shaped bacteria-It is also called cocci.

3- Spiral-shaped  bacteria- It is also called spirilla.

4- Comma-shaped bacteria- It is also called vibrio.

 

 What is aerobic bacteria?

The bacteria which need oxygen for their growth are called aerobic bacteria.

Ex- mycobacterium tuberculosis, pseudomonas aeruginosa, bacillus subtilis etc.

What is anaerobic bacteria?

The bacteria which survive without oxygen are called anaerobic bacteria.

Ex- staphylococcus, listeria, bacteroides, clostridium etc.

How many types of bacteria on the basis of nutrition ?

There are three types of bacteria on the basis of nutrition.

1- autotrophic bacteria - the bacteria which prepares their food by chemosynthesis is called autotrophic bacteria 

2- saprophytes- the bacteria that obtains their nutrition from dead and decaying organic matter. Such bacteria are called saprophytes.

3-parasitic bacteria - the bacteria that obtains food from other living organisms are called parasitic bacteria.

How does bacteria reproduce?

Bacteria reproduces by binary fission. Most bacteria divide very fast. Escherichia coli divides itself at every twenty minutes. Pseudomonas divides itself at every 9.5 minutes.

Write some diseases that are caused due to bacteria.

Some diseases that are caused due to bacteria are typhoid, Cholera, Leprosy, Tuberculosis, Plague and Syphilis.

 What is algae?

Algae are a type of plant-like living things that can make food from sunlight by photosynthesis.Algae are usually aquatic in nature. Algae is a group of eukaryotic organisms which can exist both as unicellular organisms and multicellular organisms. It has cell wall and chlorophyll.

 Write six properties of algae.

 The six properties of algae are

1- Algaes are unicellular and multicellular both.

2- Chlamydomonas is an example of unicellular algae but spirogyra is an example of multicellular algae.

3- They are autotrophic in nature.

4- They may be filamentous or branched but do not have roots, steams or leaves.

5- Most of the algae are found in water. But some algae are found in snow, hot spring, moist soil, a bark of trees and rock surfaces.

6- most algae live in water hence they are called Grass of water.

 

How many types of algae on the basis of colour pigment?

 There are three types of algae on the basis of colour pigment.

1- green algae

Ex- chlamydomonas, volvox, spirogyra, ulothrix etc

2- red algae

Ex- gelidium, polysiphonia etc

3- brown algae 

Ex- sargassum, fucus, laminarian etc

Write about the nutrition of algae

 Algae are autotrophs as they contain chlorophyll and make their food by the process of photosynthesis.

 What Is Protozoa?

These are unicellular microscopic organisms similar to animals that can move about to capture food and are heterotrophic in nature. They are mostly aquatic in nature.

Ex- Amoeba, Giardia, Plasmodium, Paramecium, euglena, entamoeba.

 

 Write four properties of protozoa.

 The four  properties of protozoa are

1- They are the most primitive unicellular and microscopic animals.

2- They are found in fresh or salt water, soil and bodies of other living organisms.

3- They are able  to move from place to place with the help of pseudopodia.

4- They are not able to make their own  food so they are heterotrophic  in nature.

5- they do not possess cellwall.

6- the body of protozoa is covered with pellicle.

7- protozoa can swim using either flagellar or cilia.

8- amoeba moves with the help of pseudopodia, paramecium swims throug cilia and euglena swims through flagella.

Write about the nutrition of protozoa.

Protozoa have animal like (holozoic) nutrition. They capture food. Some protozoans are parasitic. Parasitic protozoans feed on animal cella and cause diseases in human and domestic animals.

 Write some diseases that are caused by protozoa.

Some diseases that are caused by protozoa are Dysentery and Malaria.

 What is fungi?

Plant -like organisms that do not contain chlorophyll are called Fungi.

Write four properties of fungi.

 The four properties of fungi are.

1- some fungi are unicellular like yeast but some fungi are multicellular like mushroom, toadstool, moulds and mildews etc.

2- The example of unicellular fungi  is yeast and the example of multicellular fungi  is penicillium, Bread mould, aspergillus  and mushroom.

3- They grow best in dark , warm and moist places.

4- They are dependent for food on decaying organic matter or living beings.

5- some fungi looks like plant but do not have roots, stem, leaves or flowers.

 How many types of fungi  on the basis of food habits?

There are two types of fungi on the basis of food habits.

1- Saprophytes

2- Parasites

 What are saprophytes?

 Those fungi  that are dependent  for food on decaying organic matter are called saprophytes.

Ex:- yeast, Bread  mould, mushroom etc.

 What are parasites?

  Those fungi  that are dependent  for food on living beings are called Parasites.

Ex:- ringworm, favus etc.

Write two diseases that are caused by fungi.

 The two diseases that are caused by fungi  are

1- Athlete’s foot

2- Ring  warm

How does fungi reproduce ?

 Fungi reproduce asexually by budding (yeast) or by forming dust like spores . Spores remain in the air and help in the dispersal of fungi to distant places.

 What are viruses?

Viruses are non-cellular, microscopic infectious agents that can only replicate inside a host cell. Viruses are very small particles that can infect animals and plants and make them sick. Viruses are made up of genetic materials like DNA and are protected by a coating of protein. Viruses hijack the cells of living organisms and  then use the cell to make more viruses and take over more cells.

Ex:- Influenza virus, Bacteriophage, Ebola virus etc.

Write Five  properties of viruses.

Five  properties of viruses are

1- They are smaller than bacteria.

2- They are seen only by an electron microscope.

3- They do not have cells and do not have cell organelles.

4- They are not able to multiply or reproduce own their own.

5- Out side of the host cell, the viruses do not show any characteristics of living beings. But as it enters the host cell it starts multiplying.

Write four diseases hat are caused due to viruses.

 The four diseases hat are caused due to viruses are Influenza (Flu), Chicken pox, Polio and AIDS.

 Write five ways, how microorganisms are useful for us?

 The five ways are

1- Microorganisms help us in preparation of food items like curd and cheese.

2- Microorganisms help us  in commercial use in beverage industry to produce alcohol.

3- Microorganisms help us in agriculture to increase soil fertility.

4- Microorganisms help us in preparation  of  medicines and vaccines.

5- Microorganisms help us in cleaning the environment.

What is curdling of milk? Write its process.

 The process of curd formation from milk  is called curdling of milk.

Milk contains a sugar called lactose. Curd contains a bacterium called lactobacillus, Which help is  the formation of curd. When a little curd is added to milk, lactobacillus multiplies and converts the milk into curd. The lactose present in the milk is converted to lactic acid.

  What is fermentation?

Fermentation is the process of food processing in which sugar is converted into alcohol  and produce carbon dioxide by the action of microorganisms. This process is used to produce alcoholic beverages like Wine. It is also used to produce food items like Cake, Bread and Pastries.

Write ten  uses of microorganisms in food industry.

The ten  uses of microorganisms in food industry are

1- Bacterium like lactobacillus helps in the formation of curd.

2- Dairy product like cheese and paneer are also made by using bacteria that is lactobacillus. Lactobacillus is also know as streptococcus.

3- Unicellular fungus yeast helps in making bread, cakes and pastries.

4- Some seaweeds like Nori, Iris moss, Sea lettuce are used as food in china and japan.

5- Some substances that are obtained from particular types of algae are used in ice-cream and jellies.

6- Some specific algae are important as food for animals like fish.

7- Scientists believe that some algae can be important sources of food for all humans in future.

8- Many mushrooms are edible. Mushrooms  are  fungus  that  are rich in proteins and vitamins.

9- The fungus aspergillus is used for the production of alcohol and citric acid.

10- Aerobic bacteria like acetobacter is used for the production of vinegar.

What is nitrogen fixation?

The process of converting nitrogen gas of the air into compounds of nitrogen is called nitrogen fixation. Compounds of nitrogen is used by plant as minerals.

Bacteria like Rhizobiums  live in the roots of leguminous  plants like pea, bean and gram These bacteria form the nodules  in the roots. The bacteria , Rhizobium fix the atmospheric nitrogen and convert it into soluble form like nitrates. This fixed nitrogen is used by plants. It also increases the fertility of soil.

Some blue- green algae also fix nitrogen and increase soil fertility.

Write shorts notes on role of microorganisms  in preparation of antibiotics.

Antibiotics and vaccines come from microbes. Bacteria and fungi are used to manufacture medicines called antibiotics. Antibiotics are the medicines used to kill or stop the growth of disease-causing microbes and are used to cure diseases. Antibiotics are also used to control some diseases in animals and plants. They are not effective in viral diseases.

Ex:- Streptomycin, Tetracycline and Erythromycin are some example of antibiotics made from bacteria or fungi.

Panicillin was the first antibiotic discovered by Sir Alexander Fleming in the year 1928 From a green mould  penicillium  notatum.

Write shorts notes on role of microorganisms in preparation of vaccines.

Vaccines are substance used to produced immunity against diseases. It is a germ bearing fluid which produces  antibodies in the body of healthy person. Vaccines protect human beings and other animals from diseases.

British physician Edward Jenner  was the first person who discovered the vaccine for smallpox in 1798.

Diseases like polio, smallpox, measles, chicken-pox, hepatitis, tuberculosis, typhoid and cholera can be prevented by vaccination.

Vaccination is method of producing immunity by injecting a vaccine into the body. It  helps the body to produces antibodies to fight against diseases. Vaccination can be oral (Polio) or can be done by inserting the medicines into the blood.

What is the role of microorganisms in cleaning the environment?

Microorganisms play an important role in cleaning the environment. They clean the environment by following ways.

Bacteria, fungi and protozoa decompose the dead bodies of organisms to get food. By this way they protect the earth from being covered by dead bodies.

After decomposition by microbes, the plant and animal tissues are broken down into simpler substances which are returned back to the soil. This is called recycling of nutrients in nature.

Some bacteria decomposes sewage and other wastes in water and thus, helps in keeping the environment clean and free from pollution.

Algae makes food by photosynthesis . in the process of photosynthesis they give off oxygen and purify the environment.

Write some other uses of microorganisms .

Some other uses of microorganisms  are

1- Some bacteria and protozoa live in the digestive system of some animals like cows, goats and sheep. These microbes help the animals to digest cellulose of grass.

2- Bacteria are very useful in tobacco, leather and jute industries. The animal skin is changed into leather with the help of bacteria, This process is called tanning. Bacteria also helps to separate jute fibres from rest of the tissue.

3- Microorganisms like bacteria also helps in generating biogas. Bacteria decompose the animal wastes and leafy wastes which produce biogas and it is used as fuel.

Write shorts notes on diseases causing of microorganisms in plants and animals.

Microorganisms also cause diseases in animals and plants. Some diseases and their causing microorganisms are given below

Diseases	Causing microbes	Affected agent
Anthrax	It is caused by a bacterium.	It affects humans and cattle.
Foot and mouth	diseases is caused by a virus.	It affects the cattles.
Citrus canker	It is caused by a bacterium.	It affects trees of  Citrus fruits.
yellow vein mosaic	This diseases is caused by a virus	It affects the vegetables plants like lady’s finger .
Rust and smut of wheat.	It is caused by fungus.	It affects the crops like wheat.
Potato blight	It is caused by fungus.	It affects the plants like potatoes.

 What do you understand by communicable  disease?

Those diseases that are caused by microbes and can spread from an infected person to a healthy person through air, water, food or direct contact are called  communicable  disease.

Ex:- Flu, Hepatitis B, Measles and Tuberculosis.

Write some precautions that are taken by us to prevent from communicable diseases.

Some precautions that are taken by us to prevent from communicable diseases are as follow

1- Handle and prepare food safety.

2- Wash hand often.

3- Clean and  disinfect commonly used surfaces.

4- Cough and sneeze into your sleeve.

5-Don’t share personal item.

6- Get vaccinated.

7- Avoid touching wild animals.

What is food poisoning?

The disease caused due to the presence of large number of microorganism in the food, or due to the presence of toxic substances in food formed by the action of microorganism is called food poisoning.

Some diseases that are caused due to food poisoning are diarrhoea, vomiting and abdominal pain.

We can protect ourselves from food poisoning by using fresh food, vegetables and fruits.

What is Preservation of food?

Food Preservation is the process by which be can prevent the spoilage of food by microbes. Odur of food, taste of food and colour of food are three indicators that tell us whether a given food is suitable for consumption or not.

The two important ways to preserve food are

1- By killing the microorganisms present in the food.

2- By stoping the microorganisms from growing again.

Write eight common methods of food Preservation and explain them.

The  eight common methods of food Preservation are

1- Heating - Heating or boiling food at a high temperature kills microbes. Thus heating and boiling help us  in  food Preservation.

Ex:- Water and milk are boiled at high temperature to kill microbes.

2- salting and adding sugar –Some food items are preserved by adding salt or sugar. Due to salting the cells of the microbes lose water by osmosis.

Ex:- Amla, Raw mangoes, Tamarind etc are preserved by salting where as jams, sauces and jellies are preserved by adding sugar.

3- Adding oil and vinegar- oil and vinegar prevent the food items from bacteria because bacteria cannot live in such an environment.

Ex:- Fruits, vegetables, fish, meat and pickles are often preserved by this method.

4- Pasteurisation- This method is used to preserve Milk. In this method milk is heated to a high temperature of 70 degree Celsius for about half a minute and then cooled quickly. This kills most of the bacteria without affecting the flavours. Other food item like cheese, honey, beer, wine and juices etc are also preserved using this method.

5- Use of chemicals- Chemicals like sodium benzoate and sodium metabisulphite help to control microbial growth. They are used to preserve jams, jellies, squashes and ketchup.

6- Drying or dehydration of food- Drying helps us in removal of moisture or water from the food. This prevents  the growth of microorganisms and protects the food from getting spoil.

Some food items like cereals, pulses, spices and dry fruits are preserved by this metod.

7- Refrigeration- Refrigeration also helps us in preserving food. This method does not kill microbes but only stops  them from growing and multiplying.  This method  is effective for some days or even month only.

Some food items like milk, meat and vegetables are preserved by this method.

8- Canning- Canning also helps us in preservation of food. In this method food items are heated to 120 degree Celsius to destroy microorganisms. Canned food remains good to eat for years.

Food items like fruits and vegetables are canned by this method.

What do you mean by nitrogen fixation?

The conversion of free atmospheric nitrogen into useful nitrogen compounds is called nitrogen fixation.

Nitrogen fixation is done by bacteria, Rhizobium that is present in the root nodules of leguminous plants like peas and gram. They help in the fixation of atmospheric nitrogen into soluble compounds that can be easily absorbed by the roots of plants.