Last updated on June 28th, 2023 at 11:09 pm
Class 8 Microorganisms Friend And Foe Notes
Class 8 Microorganisms – Friend And Foe Question and Answers | Class 8 Microorganisms Question and Answers |
Q: What are microorganisms?
A: Microorganisms or microbes are living organisms that are present around us but cannot be seen with the naked eye.
Q: What are the four major groups of microorganisms?
A: The four major groups of microorganisms are bacteria, fungi, protozoa, and some algae.
Q: What is the role of microorganisms in the environment?
A: Microbes are responsible for many natural processes such as decomposition, fermentation, and nitrogen fixation.
Q: Can viruses be seen with a microscope?
A: Yes, viruses can be seen with a microscope, but they reproduce only inside the cells of a host organism.
Q: What is the importance of understanding microorganisms?
A: Understanding the different types of microorganisms and their roles in disease and the environment is important for scientific research and public health.
Q: What are some food items that are prepared using microorganisms?
A: Food items such as curd, cheese, pickles, bread, cake, idlis, and dosa batter are prepared using microorganisms.
Q: How are microorganisms used in cleaning up the environment?
A: Microorganisms can be used in cleaning up the environment by breaking down organic waste into usable substances.
Q: What is the role of microorganisms in agriculture?
A: In agriculture, microorganisms are used to increase soil fertility by fixing nitrogen.
Q: What is the importance of understanding the roles of microorganisms?
A: Understanding the roles of microorganisms is important for their use in food production, medicine, and environmental cleanup, among other applications.
Q: What microorganisms are involved in the formation of curd and fermented food products?
A: Bacteria, such as Lactobacillus, are involved in the formation of curd and other fermented food products.
Q: What is fermentation?
A: Fermentation is the process of converting sugar into alcohol by yeast, and it produces a characteristic smell.
Q: What is the large-scale production of acetic acid?
A: Microorganisms are used for the large-scale production of acetic acid (vinegar).
Q: What are antibiotics and how are they used?
A: Antibiotics are medicines produced from bacteria and fungi that kill or stop the growth of disease-causing microorganisms. They are used to cure a variety of diseases and are also mixed with livestock and poultry feed to control microbial infection.
Q: What is the role of vaccines?
A: Vaccines work by introducing dead or weakened microbes into the body, which triggers the production of suitable antibodies that protect against the disease-causing microbes for life.
Q: Name some commonly known antibiotics made from fungi and bacteria.
A: Streptomycin, tetracycline, and erythromycin are commonly known antibiotics made from fungi and bacteria.
Q: What is the Pulse Polio Programme?
A: The Pulse Polio Programme is a vaccination programme aimed at protecting children against polio.
Q: What is the role of microorganisms in vaccination?
A: Microorganisms are used to produce vaccines on a large scale to protect humans and animals from diseases.
Q: What is nitrogen fixation?
A: Nitrogen fixation is the process by which some bacteria are able to fix nitrogen from the atmosphere, enriching the soil with nitrogen and increasing its fertility.
Q: What is the role of microbes in decomposition?
A: Microbes are responsible for the decomposition of dead organic matter into simple substances that can be used by other plants and animals.
Q: Can waste materials like polythene bags, empty glasses, bottles, and broken toy parts be converted into manure by microbes?
A: No, waste materials like polythene bags, empty glasses, bottles, and broken toy parts cannot be converted into manure by microbes.
Q: What are pathogens?
Pathogens are microorganisms that cause diseases in humans, animals, and plants.
Q: How do communicable diseases spread?
Communicable diseases spread from an infected person to a healthy person through air, water, food, or physical contact.
Q: What are some examples of communicable diseases?
Common cold, cholera, tuberculosis, and chickenpox are examples of communicable diseases.
Q: How do houseflies and mosquitoes contribute to the spread of diseases?
Houseflies can act as carriers of disease-causing microbes by transferring pathogens from garbage and animal excreta to uncovered food. Female Anopheles mosquito carries the parasite of malaria, while female Aedes mosquito carries the dengue virus.
Q: What measures can be taken to control the spread of malaria or dengue?
To control the spread of malaria or dengue, it is essential to eliminate the breeding sites of mosquitoes by removing stagnant water from around the house and using mosquito nets and repellents.
Q: What are the ways in which microorganisms can spoil food?
Microorganisms can spoil food by producing toxic substances, making it poisonous and causing illness or even death. Spoiled food emits bad smell, has a bad taste, and changes color.
Q: How can we prevent spoilage of food by microorganisms?
Preservatives such as salt, sugar, sodium benzoate, sodium metabisulphite, and vinegar are commonly used to prevent spoilage of food by inhibiting the growth of microbes. Dry salting is a common method used to preserve meat and fish. Jams, jellies, and squashes are preserved by sugar. Oil and vinegar are used to prevent spoilage of pickles.
Q: What is pasteurization, and how does it prevent the growth of harmful microbes in milk?
Pasteurization is a process that involves heating and cooling milk to prevent the growth of harmful microbes. By heating the milk, the harmful microbes are killed, and then cooling the milk prevents the growth of any remaining microbes.
Q: How do certain bacteria and blue-green algae in the soil convert atmospheric nitrogen into compounds of nitrogen, which can be used by plants?
Certain bacteria and blue-green algae present in the soil fix nitrogen from the atmosphere and convert it into compounds of nitrogen. Once nitrogen is converted into these usable compounds, it can be utilized by plants from the soil through their root system.
Q: What are bacteria?
Bacteria are unicellular living organisms that can be found in air, water, soil, and living organisms. They grow and multiply quickly, producing two bacteria in 10 to 30 minutes.
Q: Define algae.
Algae are microorganisms that resemble plants and contain cell walls and chlorophyll. They can be unicellular or multicellular.
Q: How are microorganisms useful?
Microorganisms are useful in making food, alcohol, medicines (such as antibiotics), and other products.
Q: Define virus.
A virus is a tiny microorganism that can only grow inside the cells of a host, such as animals or plants. They are smaller than bacteria and lack many of the features of living organisms.
Q: Define protozoa.
Protozoa are single-celled microorganisms that can cause diseases such as dysentery and malaria.
Q: What is fermentation?
Fermentation is the process of converting sugar into alcohol using yeast.
Q: Define vaccine.
A vaccine is a type of medication that provides protection against a specific illness by triggering an immune response in the body.
Q: What is vaccination? What vaccine is given to children?
Vaccination is the practice of administering a vaccine to prevent specific illnesses. Children are commonly vaccinated against diseases such as polio, smallpox, cholera, typhoid, hepatitis, tuberculosis, tetanus, measles, and diphtheria.
Q: What are communicable diseases? Give examples.
Communicable diseases are illnesses that can spread from one person to another through air, water, food, or physical contact. Examples include the common cold, cholera, chickenpox, tuberculosis, malaria, and AIDS.
Q: Which mosquito carries dengue in humans?
The Aedes mosquito is the carrier of the dengue virus, which can spread the disease from person to person.
Q: What is food poisoning?
Food poisoning is an illness caused by the presence of harmful microorganisms or compounds in food.
Q: What are the symptoms of food poisoning?
The most common symptoms of food poisoning include vomiting, diarrhea, abdominal pain, headache, and fever.
Q: What is preservation? What are the methods of food preservation?
Preservation is the process of treating food to prevent spoilage. Methods of food preservation include sun-drying, heating, cooling, deep freezing, adding salt, sugar, mustard oil, and vinegar, using chemical preservatives, and pasteurization.
Q: What is nitrogen fixation?
Nitrogen fixation is the process of converting nitrogen gas from the environment into nitrogen compounds.
Q: Define the Nitrogen Cycle.
The nitrogen cycle is the movement of nitrogen through living things and the non-living environment in nature.
