Microorganisms: Friend and Foe

Question 1

What are Microorganisms?

Answer 1

They are living organisms present everywhere which we cannot see with unaided eye. They require special equipment like microscopes, etc for seeing.

Question 2

What are major groups of microorganisms?

Answer 2

There are four major microorganisms:
Bacteria : typhoid and tuberculosis ( lactobacillus)
Fungi : bread mould, pencillium and aspergillus ( rust of wheat )
Protozoa : dysentery and malaria, paramecium and amoeba
Algae : spirogya, chlamydomonous and sea weed

Question 3

Why are viruses different and not counted in major microorganisms?

Answer 3

Viruses are also microscopic but require a host body in order to reproduce which may be a plant, animal or bacterium. Common diseases : cold, flu and cough Serious diseases : polio and chicken pox

Question 4

Where do microorganisms live ?

Answer 4

They are single or multi cell organisms which are present in all types of environments from icey cold to hot springs ; from deserts to marshy lands.

Question 5

How are Microorganisms beneficial ?

Answer 5

They are useful to us in many ways such as :
• they are used in the making of curd, bread and cake.
• They are used in cleaning up of environment. For example organic waste at broken down into harmless and usable substances by bacteria.
• They are used in large scale production of alcohol wine and acetic acid vinegar• bacteria are also used in making of medicines.
• In agriculture they are used to increase soil fertility by fixing nitrogen, these are commonly known as biological nitrogen fixers. Ex Rhizobium
• It is turned into curved by bacteria with the help of the bacterium ‘lactobacillus’ which multiplies in milk and converts it into curd.
• Bacteria is involved in making of cheese, pickles and many other food items.
• Bacteria and yeast are also used in fermenting of idli and dosa batter.
• They are using large scale production of alcohol, wine and acetic acid (vinegar) known as fermentation.
• They are used in the making of antibiotics and are even mixed with the feed of livestock and poultry to check microbial infection in animals.
• It helps in production of antibodies in our body.
Trick : CAMFEGPCBS
Curd, alcohol, medicines, fixing nitrogen, environment clean, guts, preservatives, cheese, biogas, sewage treatment,etc

Question 6

What is yeast ?

Answer 6

Yeast is a type of ingredient which is added in items for fermentation of breads, pastries, cakes, Idli dosa batter. It is also used in large scale production of alcohol, wine and acetic acid.

Question 7

What are antibiotics ?

Answer 7

These are medicines which are made to kill or stop the growth of microorganisms. These are made from bacteria and fungi. Commonly known antibiotics are streptomycine, tetracycline and erythromycin.

Question 8

What is fermentation ? How is it done ?

Answer 8

Fermentation is the process of conversion of yeast and sugar into alcohol or wine. It is done by growing yeast upon natural sugars like barley, wheat, rice, crushed fruit juices, etc. or by keeping yeast on sugar for several hours.

Question 9

Who discovered fermentation?

Answer 9

Louis Pasteur in 1857.

Question 10

Who discovered the first antibiotic ? What was it ?

Answer 10

In 1929 Alexander Fleming created the first antibiotic called mould pencillin.

Question 11

What are the precautions to be taken while consuming antibiotics?

Answer 11

These are the precautions:
• they should be only taken with the advice of a qualified doctor.
• we should complete the course given and not stop it in between.
• We should not take antibiotics when not needed it will make the antibiotic less effective in future and it will kill the beneficial bacteria in the body.

Question 12

What is a vaccine? How does it help?

Answer 12

Vaccine is a medicine made from dead or weakened pathogens which trains the body for future invasion of them.
When a vaccine is injected the body produces antibodies to fight the invader, the antibodies created remain in the body and it remember to the fight if it comes again, if dead or weakened microbes are introduced then a healthy body can fight it easily.

Question 13

Who discovered the first vaccine?

Answer 13

Edward jenner discovered the first vaccine for small pox in 1798.

Question 14

Why are children given vaccines?

Answer 14

They are so because it is essential for eradicating a particular disease from the body at the right age and time.

Question 15

Name two campaigns in India for eradicating polio and small pox ?

Answer 15

• Pulse Polio Programme
• Against Small pox worldwide

Question 16

What are communicable diseases?

Answer 16

These are diseases which get infected from a person to another person by means of air, water or physical contact. Ex: cholera, Common cold, chicken pox and tuberculosis.

Question 17

What are carriers ?

Answer 17

These are insects and animals which transmit pathogen by carrying them. Housefly is the most common carrier.

Question 18

Why shouldn’t we eat contaminated or uncovered food?

Answer 18

We shouldn’t do so as flies act as carriers of pathogens by sitting on garbage and animal excreta and sits with same feet on our food.

Question 19

Name two carriers of protozoa.

Answer 19

Malaria ( plasmodium ) - Female anopheles mosquito
Dengue - Female aedes mosquito

Question 20

How can we prevent spreading of protozoa.

Answer 20

We can do so by stopping the growth of mosquitos. All mosquitos breed in water so we can stop their growth by eliminating water collection in coolers, tyres, flower pots, etc. and keeping our surroundings clean and dry.

Question 21

Name the Causative agents of various diseases.
Tuberculosis, measles, chicken pox, polio, cholera, typhoid, hepatitis A, malaria

Answer 21

Tuberculosis - bacteria through air
Measles - virus through air
Chicken pox - virus through air or water
Polio - virus through air or water
Cholera - Bacteria through water or food
Typhoid - Bacteria through water
Hepatitis A - virus through water
Malaria - Protozoa through mosquitos

Question 22

Name common plant diseases with their causative agent.

Answer 22

Citrus canker - Bacteria through air
Rust of wheat - fungi through air or seeds
Yellow vein of mosaic of bhindi ( okra ) - virus through insects

Question 23

How does food poisoning occur?

Answer 23

It could be due to the consumption of spoilt food by microorganisms. Sometimes, microorganisms produce toxic substances that harm us.

Question 24

What are the different types of preservation methods used in foods?

Answer 24

The following are used commonly for preservation:
- Salts and edible oils are used to check the growth of microorganisms.
- Acid preservatives in pickles, jams and squashes ( sodium benzoate, sodium metabisulphite) .
- salt for meat, fish, amla, raw mangoes and tamarind.
- sugar for jams, jellies, squashes as it reduces the moisture content inhibiting the growth of bacteria.
- oil and vinegar for pickles, vegetables, fruits, fish, and meat are preserved as bacteria can’t live in such environment.
- boiling and refridgerator as it kills many of them

Question 25

What is Pasteurisation ?

Answer 25

In this process the milk is heated to about 70 degree Celsius for 15 to 30 seconds and then suddenly chilled and stored. By doing this, milk can be consumed directly without boiling as it prevents the growth of microorganisms. This process was discovered by louis Pasteur.

Question 26

Where is Rhizobium found ?

Answer 26

It is found in the roots of leguminous plants ( pulses ) such as beans and peas.

Question 27

How is nitrogen fixed?

Answer 27

It is fixed by lightning as well as the nitrogen cycle.

Question 28

Describe the nitrogen cycle?

Answer 28

Our atmosphere has 78% of nitrogen, it is always the same as it is in constant motion. Nitrogen is one of the most important constituents as a part of proteins, chlorophyll, nucleic acid and vitamins.
The atmospheric nitrogen cannot be taken directly so certain bacteria and algae fix nitrogen from the air to the soil and converts it to compounds of nitrogen, then it is uptake by plants, animals feeding on these plants also get these nutrients and when they die the nitrogenous compounds get to the soil and certain bacteria again turn them into atmospheric nitrogen. In this way the amount of nitrogen in the atmosphere remain constant.

Question 29

Who discovered the bacterium ‘ bacillus anthracis’? what does it do?

Answer 29

Robert Kōch discovered it in 1876 which causes anthrax disease in human and cattle.