HOTS questions - Microorganisms, Friend and foe - Class 8 Science
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HOTS Questions - Class 8 Science - Chapter 2 - Microorganisms, Friend and Foe
These HOTS questions on 'Microorganisms, Friend and foe' for Class 8 will test the Higher Order Thinking Skills in Science of CBSE students and NSO Science Olympiad aspirants.
1. Which of the following statements is true about microorganisms?
a) All microorganisms are harmful to humans
b) Microorganisms cannot survive in extreme environments
c) Some microorganisms are beneficial to humans
d) Microorganisms do not play any role in the environment
Answer: c) Some microorganisms are beneficial to humans
Explanation: Microorganisms can be harmful, beneficial, or neutral to humans. Many microorganisms play important roles in the environment, such as decomposing organic matter, fixing nitrogen, and producing oxygen.
2. Which of the following microorganisms is responsible for causing malaria?
a) Bacteria
b) Virus
c) Fungi
d) Protozoa
Answer: d) Protozoa
Explanation: The protozoan parasite Plasmodium is responsible for causing malaria, a serious and sometimes fatal disease.
3. Which of the following microorganisms is used in the production of antibiotics?
a) Fungi
b) Bacteria
c) Virus
d) Protozoa
Answer: b) Bacteria
Explanation: Many antibiotics, such as penicillin, are produced by certain species of bacteria.
4. Which of the following microorganisms is used in the production of bread?
a) Fungi
b) Bacteria
c) Virus
d) Protozoa
Answer: a) Fungi
Explanation: The yeast fungi Saccharomyces cerevisiae is used in the production of bread through the process of fermentation.
5. Which of the following microorganisms is used in the production of alcohol?
a) Fungi
b) Bacteria
c) Yeast
d) Virus
Answer: c) Yeast
Explanation: Yeast is used in the production of alcohol through the process of fermentation.
6. Which of the following microorganisms is responsible for the formation of curd from milk?
a) Virus
b) Bacteria
c) Fungi
d) Protozoa
Answer: b) Bacteria
Explanation: Lactobacillus bacteria are used in the formation of curd from milk.
7. Which of the following microorganisms is used in the production of soy sauce?
a) Fungi
b) Bacteria
c) Virus
d) Protozoa
Answer: a) Fungi
Explanation: The fungi Aspergillus oryzae is used in the production of soy sauce through the process of fermentation.
8. Which of the following microorganisms is used in the production of antibiotics?
a) Fungi
b) Bacteria
c) Virus
d) Protozoa
Answer: a) Fungi
Explanation: Fungi such as Penicillium are used in the production of antibiotics.
9. Which of the following microorganisms is responsible for the formation of holes in cheese?
a) Fungi
b) Bacteria
c) Virus
d) Yeast
Answer: b) Bacteria
Explanation: Propionibacterium bacteria are responsible for the formation of holes in cheese.
10. Which of the following microorganisms is used in the production of bread?
a) Fungi
b) Bacteria
c) Yeast
d) Virus
Answer: c) Yeast
Explanation: Yeast is used in the production of bread through the process of fermentation.
11. Which of the following microorganisms is responsible for the formation of curd from milk?
a) Virus
b) Bacteria
c) Fungi
d) Protozoa
Answer: b) Bacteria
Explanation: Lactobacillus bacteria are used in the formation of curd from milk.
12. Which of the following microorganisms is used in the production of vinegar?
a) Bacteria
b) Fungi
c) Virus
d) Protozoa
Answer: a) Bacteria
Explanation: Acetobacter bacteria are used in the production of vinegar through the process of fermentation.
13. Which of the following microorganisms is responsible for the spoilage of food?
a) Fungi
b) Bacteria
c) Yeast
d) Virus
Answer: b) Bacteria
Explanation: Some types of bacteria are responsible for the spoilage of food.
14. Which of the following microorganisms is used in the production of soy sauce?
a) Bacteria
b) Fungi
c) Yeast
d) Virus
Answer: b) Fungi
Explanation: Aspergillus oryzae fungus is used in the production of soy sauce through the process of fermentation.
15. Which of the following microorganisms is used in the production of antibiotics?
a) Bacteria
b) Virus
c) Fungi
d) Algae
Answer: a) Bacteria
Explanation: Many antibiotics are produced by bacteria such as Streptomyces, which is commonly used to produce antibiotics like streptomycin and tetracycline.
HOTS Questions - Microorganisms - Fill in the blanks
1. Fill in the blank: The process of conversion of sugar into alcohol is called _______________.
a) Fermentation
b) Photosynthesis
c) Respiration
d) Digestion
Answer: a) Fermentation
Explanation: Fermentation is a process in which microorganisms like yeast convert sugar into alcohol and carbon dioxide.
2. Fill in the blank: Rhizobium bacteria convert atmospheric nitrogen into _____________ form, which is used by plants.
a) Oxygen
b) Carbon dioxide
c) Nitrate
d) Methane
Answer: c) Nitrate
Explanation: Rhizobium bacteria are nitrogen-fixing bacteria that convert atmospheric nitrogen into nitrate form, which is used by plants for their growth.
3. Fill in the blank: Penicillin is an antibiotic that is produced by the fungus _____________.
a) Aspergillus
b) Candida
c) Saccharomyces
d) Rhizopus
Answer: a) Aspergillus
Explanation: Penicillin is an antibiotic that is produced by the fungus Aspergillus.
4. Fill in the blank: _____________ bacteria are used in the production of cheese and curd from milk.
a) Lactobacillus
b) E. coli
c) Streptococcus
d) Salmonella
Answer: a) Lactobacillus
Explanation: Lactobacillus bacteria are used in the production of cheese and curd from milk.
5. Fill in the blank: The process of conversion of atmospheric nitrogen into a form that can be used by plants is called _____________.
a) Photosynthesis
b) Respiration
c) Nitrogen fixation
d) Fermentation
Answer: c) Nitrogen fixation
Explanation: Nitrogen fixation is the process of conversion of atmospheric nitrogen into a form that can be used by plants for their growth.
6. Fill in the blank: The study of microorganisms is called _____________.
a) Biology
b) Microscopy
c) Microbiology
d) Biotechnology
Answer: c) Microbiology
Explanation: Microbiology is the study of microorganisms like bacteria, viruses, fungi, protozoa, etc.
7. The process of converting sugar into alcohol is called _________ .
a) Fermentation
b) Respiration
c) Photosynthesis
d) Transpiration
Answer: a) Fermentation
Explanation: Fermentation is the process of conversion of sugar into alcohol by yeast or bacteria in the absence of oxygen.
8. Antibiotics are effective only against __________ .
a) Viruses
b) Bacteria
c) Fungi
d) Algae
Answer: b) Bacteria
Explanation: Antibiotics are drugs that are used to treat bacterial infections.
9. The process of nitrogen fixation is carried out by _________ .
a) Bacteria
b) Virus
c) Fungi
d) Protozoa
Answer: a) Bacteria
Explanation: Nitrogen fixation is the process by which atmospheric nitrogen is converted into a usable form of nitrogen by certain bacteria such as Rhizobium.
10. The process of conversion of nitrate into nitrogen gas is called __________ .
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
Answer: c) Denitrification
Explanation: Denitrification is the process by which nitrate is converted into nitrogen gas by certain bacteria such as Pseudomonas and Bacillus.
11. The process of conversion of atmospheric nitrogen into nitrates is called _________ .
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
Answer: b) Nitrification
Explanation: Nitrification is the process by which atmospheric nitrogen is converted into nitrates by certain bacteria such as Nitrosomonas and Nitrobacter.
12. The disease that is caused by a virus is __________ .
a) Malaria
b) Tuberculosis
c) Influenza
d) Typhoid
Answer: c) Influenza
Explanation: Influenza is a viral disease that affects the respiratory system.
13. The process by which bacteria take up nutrients from dead and decaying organic matter is called __________ .
a) Decomposition
b) Fermentation
c) Ammonification
d) None of the above
Answer: a) Decomposition
Explanation: Decomposition is the process by which bacteria and fungi break down dead and decaying organic matter into simpler compounds.
14. The process by which certain bacteria convert ammonia into nitrites and then nitrates is called __________ .
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
Answer: b) Nitrification
Explanation: Nitrification is the process by which certain bacteria convert ammonia into nitrites and then nitrates.
15. The process of conversion of nitrogenous compounds into ammonia is called __________ .
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
Answer: d) Ammonification
Explanation: Ammonification is the process by which nitrogenous compounds such as proteins and nucleic acids are broken down into ammonia by certain bacteria and fungi.
Microorganisms: Friend and foe - PDF Sample paper
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Revision notes - CBSE Class 8 Science Chapter 2 - Microorganisms : Friend and Foe
1. Introduction
- Microorganisms are tiny living organisms that can be found everywhere, including in soil, water, air, and even inside our bodies. - Some microorganisms are beneficial and essential for our survival, while others can cause diseases and damage to living organisms.
2. Where do Microorganisms Live?
- Microorganisms can live in various environments, including soil, water, air, and inside living organisms. - Some microorganisms, such as thermophiles, can survive in extreme environments such as hot springs and deep-sea hydrothermal vents.
3. Beneficial Microorganisms
- Some microorganisms are used to produce food and beverages, such as bread, yogurt, cheese, and wine. - Microorganisms are also used in the production of antibiotics and other medicines. - Certain bacteria and fungi are used in the nitrogen cycle, which is important for plant growth.
4. Harmful Microorganisms
- Some microorganisms can cause diseases in plants, animals, and humans. - Bacteria and viruses are responsible for many diseases, such as tuberculosis, pneumonia, and the flu. - Fungi can cause skin infections and diseases such as ringworm.
5. Food Preservatives
- Microorganisms can cause food spoilage and contamination, which can lead to foodborne illnesses. - Food preservatives, such as salt, vinegar, and citric acid, can be used to prevent the growth of harmful microorganisms and increase the shelf life of food.
6. Nitrogen Fixation
- Nitrogen is an essential element for plant growth, but most plants cannot use atmospheric nitrogen directly. - Certain bacteria, such as rhizobia, can convert atmospheric nitrogen into a form that plants can use, a process called nitrogen fixation. - Leguminous plants, such as peas and beans, have a symbiotic relationship with nitrogen-fixing bacteria, which helps them to grow and produce more food.
7. Nitrogen Cycle
- The nitrogen cycle is the process by which nitrogen is converted into different forms and circulated in the ecosystem. - Nitrogen fixation, nitrification, and denitrification are the main processes involved in the nitrogen cycle. - The nitrogen cycle is important for maintaining soil fertility and supporting plant growth.
8. Prevention and Control of Microbial Diseases
- Preventing the spread of diseases is important to keep people healthy. - Methods of preventing the spread of diseases include washing hands regularly, covering your mouth when you cough or sneeze, and avoiding contact with infected people. - Antibiotics can be used to treat bacterial infections, but they should only be used when necessary to prevent the development of antibiotic-resistant bacteria.
9. Microorganisms in the Environment
- Microorganisms play an important role in the environment. - They are responsible for decomposing dead plant and animal matter, which helps to recycle nutrients in the ecosystem. - Some microorganisms are used in bioremediation, which involves using microorganisms to break down pollutants in the environment.
10. Conclusion
- Microorganisms can be both friend and foe depending on their role. - Understanding microorganisms and their functions can help us to use them in beneficial ways and control their harmful effects.