Chapter NO.1
MICROORGANISMS (Friend and Foe)
Q1. What are Microorganisms and what are their types?
Microorganisms:- The organisms which are small and cannot be seen with naked eye but can only be seen under a microscope are called Microorganisms. They exist in all types of habitats. Microorganisms may be either single celled like bacteria, protozoa etc or multi-cellular like algae, fungi.The various types of Microorganisms are:
(i) Bacteria (ii) Fungi (iii) Protozoa (iv) Algae (v) Virus
Q2. What are beneficial aspects of bacteria?
Microorganisms play
an important role in our lives. Some of them are beneficial in many
ways as under :
i. They are used in the production of antibiotics like penicillin etc.
ii. They are used in the production of Diary products like, Curd,
Cheese etc.
iii. They are used in the production of bakery products like bread
and cakes.
iv. They are used in the production of Alcoholic beverages like
wines, beers etc.
v. They are used in the production of enzymes.
vi. They are used in the decomposition of organic matter.
vii. They are used in the tanning of leather.
viii. They are used in the production of organic acids.
ix. They are used in the production of food yeast.
x. They are also used in cleaning up the environment e.g. organic
wastes like vegetable peels, remains of animals etc.
Q3. What are harmful effects of Microorganisms?
Microorganisms are harmful in many ways
i. Some microorganisms called pathogens cause a large variety of
diseases in plants, animals and human beings.
ii. Some microorganisms spoil food, clothing, leather etc.
iii. Microbes also cause water pollution i.e., death of aquatic life in
water resources.
Q4. What are Antibiotics? Give examples.
Antibiotics are drugs or chemicals derived from living matter or microorganisms used to kill or prevent the growth of other microorganisms e.g. Ampicillin, Penicillin, Chloramphenicol, Amoxicillin, Tetracycline, Tobramycin etc
Q5. Name some diseases caused by Microorganisms in humans.
The common diseases caused by microbes are:
A. Viruses:- Common cold, Influenza, Rabies, Smallpox, Measles, Fever, AIDs, Mumps etc.
B. Bacteria:- Cholera, Tuberculosis, Typhoid, Pneumonia, Tetanus, Leprosy etc.
C. Protozoa:- Malaria, Amoebic dysentery, Sleeping sickness, Black fever etc.
D. Fungi:- Ringworm, Athlete’s Foot, Skin Sore etc
Q6. Name some common plant diseases caused by Microorganisms.
Several microorganisms cause diseases in plants like Wheat, Rice,
Potato, Sugarcane, Orange, Apple. Some of the diseases are as under:
i. Black Rot of Cabbage Bacteria
ii. Late Blight of Potato Fungi
iii. White Rust of Mustard Fungi
iv. Rice blast of Rice Fungi
v. Rust of Wheat Fungi
vi. Yellow Vein Mosaic Virus of lady finger.
Q7. What is Food preservation? Name different types of Food Preservation.
Food preservation is the process or treating and
handling food to stop or slow down food spoilage, loss of quality,
edibility or nutritional value and thus allow for longer food storage. some of the methods or types of food preservation are:
(i) Dehydration/Drying
(ii)
Pickling i.e. Food preserved in vinegar.
(iii) Smoking
(iv)
Canning
(v) Bottling
(vi) Refrigeration
(vii) Sterilization
(viii) Pasteurization
(ix) Chemical preservation or chemical
additives like Acetic acid, Lactic acid or benzoic acid.
Q8. What is Nitrogen Fixation?
The process of conversion of atmospheric nitrogen into combined form i.e. Nitrates or Nitrites of Ammonia through chemical and biological action of bacteria like Rhizobium. The nitrogen gas of air can be fixed i.e. converted into nitrogen compounds by certain nitrogen fixing bacteria present in the soil e.g. Rhizobium bacteria present in the nodules of leguminous plants like pea and beans, blue green algae and lightning.
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Q9. What is nitrogen Cycle?
The atmosphere has 78% nitrogen. The nitrogen
fixing bacteria present in air, soil and root nodules of leguminous
plants, blue green algae and lightning in the sky fix i.e. convert free
nitrogen gas of air into compounds of nitrogen which go into soil.
The plants in the soil convert the compounds of nitrogen into plant
proteins and other organic compounds for their body development.
Animals feeding on plants convert plant proteins into animal proteins
and other organic compounds to make up their body. On one hand
after death and decay of plants, animals and other animal excretions
get decomposed and converted in simple compounds of nitrogen by certain bacteria and fungi present in the soil. All the simple
compounds of nitrogen formed in this way go back into soil.
On the other hand some compounds of nitrogen formed from decay of
dead plants, animals and their excreta are decomposed by denitrifying
bacteria present in the soil to form nitrogen gas which goes back freely
into the atmosphere again.
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