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Question 2

List out any two important landmarks in the study of microorganisms.

Genetics and Microbiology are the two important landmarks in the study of microorganisms.


Question 3

State any one useful effect of microorganisms in our life.

It is used in the production of antibiotics.


Question 4

Name three habitats of microorganisms.

Desert soil, marshy land and water are the three habitats of microorganisms.


Question 5

Name any two food items that are prepared using yeast.

Bread and wine are the two food items that are prepared using yeast.


Question 6

Name any five protozoans known to you.

Amoeba, Plasmodium,Paramecium Entamoeba and Trypanosoma.


Question 7

What do you understand by microorganisms? Describe their useful and harmful effects.

Microorganisms are very small and can survive in almost all kinds of environmental conditions. The microorganisms help in decomposition of wastes in sewage treatment plants. Yeasts are unicellular and saprophytic fungi, which are used in fermentation to produce beer, wine and other beverages.

Harmful effects of microorganims are, some of the fungi damage and spoil food products, leather, paper and textiles, whereas others are pathogenic to crops and animals. Protozoans cause serious diseases like dysentery and malaria.


Question 8

Write a note on the animal diseases caused by microorganism ?

Some Diseases Caused by Microorganisms
Disease Symptoms Remarks
Mumps Painful swelling near the jaw on one or both sides. Mumps in males over the age of 11 may affect the testes, but it rarely results in sterility.
Chicken pox Small red spots which turn to blisters, andthen to scabs. Chicken pox affects children mildly but in adults it is severe. The same virus causes shingles.
Rabies Fever, delirium, convulsions, paralysis. The throat muscles tighten so that it is impossible even to drink. Rabies can infect all animals - fox, bats, etc. but it is mainly a serious risk to human beings ,if domestic animals are infected.
Tuberculosis cough and damage to lungs. Many people who are infected by TB germs do not develop TB. They develop a natural immunity to TB.
Typhoid Fever, constipation, dry cough. Can be prevented by proper sewage disposal.
Cholera diarrhoea, dehydration and collapse. Can be prevented by using clean water and clean food.

Question 9

Write a note on the plant diseases caused by microorganism?

Plant diseases Micro organism Mode of transmission
Citrus canker Bacteria Air
Rust of wheat fungi Air seeds
Yellow vein Virus Insect mosaic of bhindi (Okra) Virus Insect

Question 10

Write an short note essay on the beneficial aspects of microorganisms.

Microbes improve soil aggregation, which influences soil-water movement and aeration. They enhance nutrient levels through nutrient cycling and organic-matter decomposition. They are essential in developing soil organic matter. Microbes degrade, mineralize and immobilize materials (organic matter, pesticides, and fertilizers) that turf managers apply to the soil. Microbes also form symbiotic (mutually beneficial) relationships with plants.

Question 11

Write the methods of food preservation

Food Preservation

Chemical Method

Sodium benzoate and sodium metabisulphite are common preservatives. These are also used in the jams and squashes to check their spoilage.

Preservation by Common Salt

Salting is also used to preserve Alma, raw mangoes, tamarind,

Preservation by Sugar

Jams, jellies and squashes are preserved by sugar.

Preservation by Oil and Vinegar

Use of oil and vinegar prevents spoilage of pickles

Heat and Cold Treatments

Boiling kills many microorganisms. Low temperature inhibits the growth of microbes.

Storage and Packing

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