Explore topic-wise InterviewSolutions in .

When a vaccine is given which contains weak microorganisms our body learn to fight them by producing antibodies whenever danger comes. When the disease causing microorganisms enter in our body, the already present antibodies fight and eliminate them. And the disease is controlled. The weakened disease causing microorganisms which are injected into our bodies are called as vaccine.

B.C.G (Bacillus Cardio Gram)

1. Pasteurisation is a process which helps in the preservation of the milk. 

2. It is discovered by “Louis Pasteur.” Hence it is called as pasteurisation. 

3. In this process milk is heated up to 70° for 15 to 30 seconds and suddenly chilled and stored. 

4. This prevents the growth of the microorganisms.

Tet – vac is the vaccine that is used to prevent Tetanus.

The Right option is : (b) Virus

Protozoa is closer to animals as it has some animal-like characters, it can move from place to place, it has no cell wall.

(b) carbon dioxide 

The process of conversion of atmospheric nitrogen into nitrogenous compounds is called nitrogen fixation.

Nitrogen-fixing bacteria can convert atmospheric nitrogen into nitrogenous compounds. Nitrogen fixation also occurs through lightning.

Certain nitrogen-fixing bacteria present in the soil like Azotobacter and Clostridium convert atmospheric free nitrogen into nitrogenous compounds like nitrites and nitrates thus enriching the soil with nitrogen and increasing fertility of the soil.

Swine flu virus will affect pigs. Similarly, bird flu virus affects birds. Some virus causes disease in plants. In humans, viral diseases are flu, chicken pox, AIDS and many more. Varicella virus causes chicken pox, HIV causes AIDS etc. Because a virus needs a host to multiply, so it can be plant, animal or human.

Yes, the decomposition of the bodies of dead plants and animals by microorganisms is desirable because if they would not be decomposed by microbes they would remain as such in the environment occupying lots of space and causing pollution. Thus microbes decompose them into simpler substances and help in cleaning the environment.

A vaccine consists of dead or weakened microbes which produce suitable antibodies when introduced into a healthy body. These antibodies remain inside our body and protect from disease-causing microbes thus provides immunity.

(c) antibiotics

(d) alga and fungus

Leguminous plants can fix nitrogen gas of air into compounds of nitrogen.

Rhizobium bacterium is present in root nodules of these plants which help in nitrogen fixation. They convert atmospheric nitrogen into nitrites and nitrates.

Fermentation

Curd contains Lactobacillus bacterium which makes idlis and bhaturas soft and spongy.

Sodium benzoate and sodium metabisulphite are common preservatives added to pickles to check the growth of microbes and prevent them from spoilage.

Alexander Fleming discovered the first antibiotic. The first antibiotic is Penicillin from fungus Penicillium notatum discovered in 1929.

Nitrogen is an element present in atmosphere that is essential for living organisms.

It is an important constituent of proteins, chlorophyll, nucleic acids, vitamins etc.

Louis Pasteur: He was a French microbiologist born in 1822. He discovered pasteurization, fermentation process, the principle of vaccination etc. He found Germ theory of disease along with Robert Koch. He is regarded as father of microbiology. He discovered vaccine for rabies and anthrax. He shows that many microbes spoil beverages like alcohol, beer, milk etc. So he invented a process called pasteurization where liquids like milk are heated to 60-100oC where most microbes get killed and then cooled suddenly. This process prevents the spoilage of liquids like alcohol, milk etc. He founded an institute which bears his name. He has worked a lot on sericulture too.

Yeast is used in preparing bread, pastries, cakes, wine. As yeast helps in fermentation process so it is widely used in baking and alcohol industry.

The yeast rapidly reacts with sugar in the dough and reproduce and produces carbon dioxide during respiration.

The bubbles of the gas fill the dough and increase its volume.

This the main reason behind the rise of dough when yeast is added to it.

(b) Waste in pit B degraded faster than that in pit A.

(a) antibodies     (b) tuberculosis  

(c) Anthrax       (d) fermentation

(a)-(iii); (b) (ii); (c)-(iv); (d)-(i)

Viruses are an interesting type of microorganisms. They usually made up of crystalized proteins. They behave like nonliving things when they are outside of a living cell. But they behave like living organisms when they are inside host living cells and reproduce just like bacteria. Hence viruses can also call as connecting links between living and nonliving things.

1. Fermentation of dosa dough will not take place. 

2. The volume of the dosa dough will not increase and it will not turn into spongy texture.

a) The diseases which spread from infected people to healthy ones are known as “communicable diseases”. 

Eg: Conjuctivitis, Common cold, Smallpox, Rubella, Typhoid, etc… 

b) The insects and animals which carry disease causing microorganisms are called as “vectors”. 

c) Female Anopheles mosquito. 

d) By controlling mosquito population.

1. The main reasons for the spread of cholera is consumption of contaminated food and water. House flies rapidly spread this disease among people. 

2. I would imagine that people were not following personal hygienic practices before consuming food and water. 

3. Perhaps people might not be keeping their surroundings clean and hygienic. 

4. Perhaps the people might have poor sanitary conditions.

(a) Preservatives 

(b) Rhizobium 

(c) Carrier/vector 

(d) Antibiotics

1. In Greek language, symbiosis means “living together”. 

2. Symbiosis is any type of a close and long term biological interaction between two different biological organisms in which both are benefited.

3. Examples for symbiotic relationship is Rhizobium. Rhizobium bacteria is living in the root nodules of legume plants. 

4. Rhizobium fixes the atmospheric nitrogen in the form of nitrates which are very essential for the growth of plants. Inturn legume plants provide shelter for Rhizobium. Here, both are benefited. 

5. Another example for symbiosis is Lichens. Here, we can see the symbiotic relationship between Algae and Fungi.

a) We feel a new variety of smell from one of the bowls. This is the characteristic smell of alcohol. There is no smell from another bowl.

b) Sugars are converted into alcohol by yeast. This process of conversion of sugars into alcohol is known as fermentation.

1. Drying 

2. Smoking 

3. Canning 

4. Chilling

Microorganisms are too small so they cannot be seen with naked eye. They can be seen with the help of a magnifying glass or microscope

Bacteria such as Rhizobium and certain blue-green algae can fix atmospheric nitrogen in the soil.

1. Microorganisms like Bacteria, Fungi which decompose the fallen plant parts, dung and vegetable peelings into simple chemical compounds. 

2. They form ‘useful manure’ to the plants since this manure is formed naturally from biological activity of microorganisms, they are called ‘bio – fertilizers’. 

3. Farmers are benefited economically. They don’t need chemical fertilizers to increase the soil fertility. Hence, Bio – fertilizers are considered as “friends of farmers”.

Micro-organisms cause diseases in animals. For example, in humans, bacteria cause diseases such as tuberculosis, cholera, typhoid, etc. In cattle, the foot and mouth disease is caused by a virus. Also, several microbes cause diseases in plants. For example, the productivity of wheat, orange, apple, etc. is reduced due to microbial diseases in plants. Certain microbes, on entering into our body, produce toxic substances. This leads to food poisoning. Some micro-organisms such as fungus spoil our food. For example, bread when left unused under moist conditions gets spoilt by fungus, producing a white cotton-like growth on the bread. 

Micro-organisms are too small to be seen through naked eyes. However, they are vital to plants and the environment. 

(i). Lactobacillus is used to form curd from milk. 

(ii). Rhizobiums present in the roots of pulse plants fix nitrogen from air and supply nitrogen compounds to the pulse plants. 

(iii). Micro-organisms are also used in winemaking, baking, pickling, and other food making processes. 

(iv). Alcoholic fermentation by yeast is widely used in the preparation of wine and bread. 

(v). Microbes are used to reduce pollution. For example, decomposers such as bacteria and fungi break down dead bodies and excreta to form inorganic compounds, which can be absorbed by plants. 

(vi). Microbes also play an important role in the preparation of medicines. Antibiotics are chemicals produced by micro-organisms to kill bacteria. Penicillin is an antibiotic made from Penicillium. 

(vii). Bacteria present in our intestine helps in proper digestion and release Vitamin B which is absorbed by intestine. 

(viii). Many vaccines are prepared from micro-organisms. These vaccines are given to children to protect them from disease. 

(ix). Certain microbes are also used in the biological treatment of sewage and industrial effluents. 

(x). Yeast is used in making idli, bhaturas, bread, pastries and cakes.

1. Microorganisms are useful and some are harmful. 

2. Some microorganisms are useful in formation process, medicine preparation and increase soil fertility. 

3. Some microorganisms are harmful by causing diseases and spoling food items.

Whenever a disease causing microorganisms enter in our body, it produces some defenders to fight against them, these are called antibodies.

Whenever a disease causing microorganisms enter in our body, it produces some defenders to fight against them, these are called antibodies. The lymphocytes of white blood cells develop antibodies against to the antigen of pathogen. Antibodies fight the disease causing microorganisms and make resistant to particular strains. Antibodies are used by the immune system to identify and neutralize foreign objects such as viruses and bacteria.

Microorganisms are present everywhere, they are to be found in air, water, soil within the bodies of animals and plants. Some microorganisms are very useful and help us in many ways while some of them are harmful. Microorganisms are most essential to maintain inorganic and organic cycles, to give freshness to the nature by degrading waste organic matter and as well as to fight against harmful microorganisms. Hence no life will be sustained in the nature if there are no microorganisms on the earth.

1. Microorganisms are the decomposers of the earth. 

2. They decompose the organic matter from plant parts and dead animals. They enrich the soil with organic matter again. 

3. Thus, they maintain the soil fertility and eliminate the wastes from the earth. 

4. I appreciate the role played by decomposers in scavenging the earth by decomposing the organic matter of dead bodies.

At birth, a baby’s digestive system is a sterile, undiscovered continent. Within minutes, microbes have started pouring in from every direction. They come from the birth canal, from the mother’s breast milk, from the fingertips of nurses and the lips of happy relatives. There are also innumerable colonies of E. coli in biotechnology and microbiology labs around the world. Everyday pharmaceutical companies manipulate E. coli to produce human growth hormone, insulin, vitamins, and even the rennet used to make cheese. Biologists use E. coli to map metabolic pathways. Scientists are even using E. coli try to understand why we age and die. 

Nitro bacter, ammonifying bacteria etc., are more useful for decompositions and fixing of Nitrogen in the plants and soil.

The soil is home to a large proportion of the world’s biodiversity. The top eight inches of soil of one acre area may contain as much as five and half tons of bacteria and fungi. Soil organisms breakdown organic matter, making nutrients available for uptake by plants and other organisms. A gram of garden soil contains around one million fungi, such as yeasts and moulds. Bacteria and fungi play key roles in maintaining a healthy soil. They act as decomposers that break down organic materials to produce detritus and other breakdown products. Soil detritivores, like earthworms, ingest detritus and decompose it.

Invention of microscope is most important one to find out microorganisms. Basing on this several inventions were made, which break the unsolved problems since 400 years. This credit goes to Antonie van Leeuwenhoek who invented single lens powerful microscope, which could magnify the object 300 times. His curiosity and skill of making powerful lenses were the secrets of this invention of powerful microscope. Later several microbes were identified by using microscopes. This provides a good source to recognize several diseases and treatment by vaccines and antibiotics.